Polymerisable compounds and the use thereof in liquid-crystal displays

ABSTRACT

The present invention relates to polymerizable compounds, to processes and intermediates for the preparation thereof, to liquid-crystal (LC) media comprising them, and to the use of the polymerizable compounds and LC media for optical, electro-optical and electronic purposes, in particular in LC displays, especially in LC displays of the polymer sustained alignment type.

The present invention relates to polymerizable compounds, to processesand intermediates for the preparation thereof, to liquid-crystal (LC)media comprising them, and to the use of the polymerizable compounds andLC media for optical, electro-optical and electronic purposes, inparticular in LC displays, especially in LC displays of the polymersustained alignment type.

BACKGROUND OF THE INVENTION

The liquid-crystal displays (LC displays) used at present are usuallythose of the TN (“twisted nematic”) type. However, these have thedisadvantage of a strong viewing-angle dependence of the contrast.

In addition, so-called VA (“vertically aligned”) displays are knownwhich have a broader viewing angle. The LC cell of a VA display containsa layer of an LC medium between two transparent electrodes, where the LCmedium usually has a negative dielectric anisotropy. In the switched-offstate, the molecules of the LC layer are aligned perpendicular to theelectrode surfaces (homeotropically) or have a tilted homeotropicalignment. On application of an electrical voltage to the twoelectrodes, a realignment of the LC molecules parallel to the electrodesurfaces takes place.

Furthermore, OCB (“optically compensated bend”) displays are known whichare based on a birefringence effect and have an LC layer with aso-called “bend” alignment and usually positive dielectric anisotropy.On application of an electrical voltage, a realignment of the LCmolecules perpendicular to the electrode surfaces takes place. Inaddition, OCB displays normally contain one or more birefringent opticalretardation films in order to prevent undesired transparency to light ofthe bend cell in the dark state. OCB displays have a broader viewingangle and shorter response times compared with TN displays.

Also known are so-called IPS (“in-plane switching”) displays, whichcontain an LC layer between two substrates, where the two electrodes arearranged on only one of the two substrates and preferably haveintermeshed, comb-shaped structures. On application of a voltage to theelectrodes, an electric field which has a significant component parallelto the LC layer is thereby generated between them. This causesrealignment of the LC molecules in the layer plane.

Furthermore, so-called FFS (“fringe-field switching”) displays have beenreported (see, inter alia, S. H. Jung et al., Jpn. J. Appl. Phys.,Volume 43, No. 3, 2004, 1028), which contain two electrodes on the samesubstrate, one of which structured in a comb-shaped manner and the otheris unstructured. A strong, so-called “fringe field” is therebygenerated, i.e. a strong electric field close to the edge of theelectrodes, and, throughout the cell, an electric field which has both astrong vertical component and also a strong horizontal component. FFSdisplays have a low viewing-angle dependence of the contrast. FFSdisplays usually contain an LC medium with positive dielectricanisotropy, and an alignment layer, usually of polyimide, which providesplanar alignment to the molecules of the LC medium.

FFS displays can be operated as active-matrix or passive-matrixdisplays. In the case of active-matrix displays, individual pixels areusually addressed by integrated, non-linear active elements, such as,for example, transistors (for example thin-film transistors (“TFTs”)),while in the case of passive-matrix displays, individual pixels areusually addressed by the multiplex method, as known from the prior art.

Furthermore, FFS displays have been disclosed (see S. H. Lee et al.,Appl. Phys. Lett. 73(20), 1998, 2882-2883 and S. H. Lee et al., LiquidCrystals 39(9), 2012, 1141-1148), which have similar electrode designand layer thickness as FFS displays, but comprise a layer of an LCmedium with negative dielectric anisotropy instead of an LC medium withpositive dielectric anisotropy. The LC medium with negative dielectricansiotropy shows a more favourable director orientation that has lesstilt and more twist orientation compared to the LC medium with positivedielectric anisotropy, as a result of which these displays have a highertransmission. The displays further comprise an alignment layer,preferably of polyimide provided on at least one of the substrates thatis in contact with the LC medium and induces planar alignment of the LCmolecules of the LC medium. These displays are also known as “UltraBrightness FFS (UB-FFS)” mode displays. These displays require an LCmedium with high reliability.

The term “reliability” as used hereinafter means the quality of theperformance of the display during time and with different stress loads,such as light load, temperature, humidity, voltage, and comprisesdisplay effects such as image sticking (area and line image sticking),mura, yogore etc. which are known to the skilled person in the field ofLC displays. As a standard parameter for categorising the reliabilityusually the voltage holding ration (VHR) value is used, which is ameasure for maintaining a constant electrical voltage in a test display.The higher the VHR value, the better the reliability of the LC medium.

In VA displays of the more recent type, uniform alignment of the LCmolecules is restricted to a plurality of relatively small domainswithin the LC cell. Disclinations may exist between these domains, alsoknown as tilt domains. VA displays having tilt domains have, comparedwith conventional VA displays, a greater viewing-angle independence ofthe contrast and the grey shades. In addition, displays of this type aresimpler to produce since additional treatment of the electrode surfacefor uniform alignment of the molecules in the switched-on state, suchas, for example, by rubbing, is no longer necessary. Instead, thepreferential direction of the tilt or pretilt angle is controlled by aspecial design of the electrodes.

In so-called MVA (“multidomain vertical alignment”) displays, this isusually achieved by the electrodes having protrusions which cause alocal pretilt. As a consequence, the LC molecules are aligned parallelto the electrode surfaces in different directions in different, definedregions of the cell on application of a voltage. “Controlled” switchingis thereby achieved, and the formation of interfering disclination linesis prevented. Although this arrangement improves the viewing angle ofthe display, it results, however, in a reduction in its transparency tolight. A further development of MVA uses protrusions on only oneelectrode side, while the opposite electrode has slits, which improvesthe transparency to light. The slitted electrodes generate aninhomogeneous electric field in the LC cell on application of a voltage,meaning that controlled switching is still achieved. For furtherimprovement of the transparency to light, the separations between theslits and protrusions can be increased, but this in turn results in alengthening of the response times. In so-called PVA (“patterned VA”)displays, protrusions are rendered completely superfluous in that bothelectrodes are structured by means of slits on the opposite sides, whichresults in increased contrast and improved transparency to light, but istechnologically difficult and makes the display more sensitive tomechanical influences (“tapping”, etc.). For many applications, such as,for example, monitors and especially TV screens, however, a shorteningof the response times and an improvement in the contrast and luminance(transmission) of the display are demanded.

A further development are displays of the so-called PS (“polymersustained”) or PSA (“polymer sustained alignment”) type, for which theterm “polymer stabilised” is also occasionally used. In these, a smallamount (for example 0.3% by weight, typically <1% by weight) of one ormore polymerizable, compound(s), preferably polymerizable monomericcompound(s), is added to the LC medium and, after filling the LC mediuminto the display, is polymerized or crosslinked in situ, usually by UVphotopolymerization, optionally while a voltage is applied to theelectrodes of the display. The polymerization is carried out at atemperature where the LC medium exhibits a liquid crystal phase, usuallyat room temperature. The addition of polymerizable mesogenic orliquid-crystalline compounds, also known as reactive mesogens or “RMs”,to the LC mixture has proven particularly suitable.

Unless indicated otherwise, the term “PSA” is used hereinafter whenreferring to displays of the polymer sustained alignment type ingeneral, and the term “PS” is used when referring to specific displaymodes, like PS-VA, PS-TN and the like.

Also, unless indicated otherwise, the term “RM” is used hereinafter whenreferring to a polymerizable mesogenic or liquid-crystalline compound.

In the meantime, the PS(A) principle is being used in variousconventional LC display modes. Thus, for example, PS-VA, PS-OCB, PS-IPS,PS-FFS, PS-UB-FFS and PS-TN displays are known. The polymerization ofthe RMs preferably takes place with an applied voltage in the case ofPS-VA and PS-OCB displays, and with or without, preferably without, anapplied voltage in the case of PS-IPS displays. As can be demonstratedin test cells, the PS(A) method results in a pretilt in the cell. In thecase of PS-OCB displays, for example, it is possible for the bendstructure to be stabilised so that an offset voltage is unnecessary orcan be reduced. In the case of PS-VA displays, the pretilt has apositive effect on response times. For PS-VA displays, a standard MVA orPVA pixel and electrode layout can be used. In addition, however, it isalso possible, for example, to manage with only one structured electrodeside and no protrusions, which significantly simplifies production andat the same time results in very good contrast at the same time as verygood transparency to light.

Furthermore, the so-called posi-VA displays (“positive VA”) have provento be a particularly suitable mode. Like in classical VA displays, theinitial orientation of the LC molecules in posi-VA displays ishomeotropic, i.e. substantially perpendicular to the substrates, in theinitial state when no voltage is applied. However, in contrast toclassical VA displays, in posi-VA displays LC media with positivedielectric anisotropy are used. Like in the usually used IPS displays,the two electrodes in posi-VA displays are arranged on only one of thetwo substrates, and preferably exhibit intermeshed and comb-shaped(interdigital) structures. By application of a voltage to theinterdigital electrodes, which create an electrical field that issubstantially parallel to the layer of the LC medium, the LC moleculesare transferred into an orientation that is substantially parallel tothe substrates. In posi-VA displays polymer stabilisation, by additionof RMs to the LC medium which are polymerized in the display, has alsoproven to be advantageous, as a significant reduction of the switchingtimes could thereby<be realised.

PS-VA displays are described, for example, in EP 1 170 626 A2, U.S. Pat.No. 6,861,107, U.S. Pat. No. 7,169,449, US 2004/0191428 A1, US2006/0066793 A1 and US 2006/0103804 A1. PS-OCB displays are described,for example, in T.-J-Chen et al., Jpn. J. Appl. Phys. 45, 2006,2702-2704 and S. H. Kim, L.-C-Chien, Jpn. J. Appl. Phys. 43, 2004,7643-7647. PS-IPS displays are described, for example, in U.S. Pat. No.6,177,972 and Appl. Phys. Lett. 1999, 75(21), 3264. PS-TN displays aredescribed, for example, in Optics Express 2004, 12(7), 1221.

Like the conventional LC displays described above, PSA displays can beoperated as active-matrix or passive-matrix displays. In the case ofactive-matrix displays, individual pixels are usually addressed byintegrated, non-linear active elements, such as, for example,transistors (for example thin-film transistors (“TFTs”)), while in thecase of passive-matrix displays, individual pixels are usually addressedby the multiplex method, as known from the prior art.

The PSA display may also comprise an alignment layer on one or both ofthe substrates forming the display cell. The alignment layer is usuallyapplied on the electrodes (where such electrodes are present) such thatit is in contact with the LC medium and induces initial alignment of theLC molecules. The alignment layer may comprise or consist of, forexample, a polyimide, which may also be rubbed, or may be prepared by aphotoalignment method.

In particular for monitor and especially TV applications, optimisationof the response times, but also of the contrast and luminance (thus alsotransmission) of the LC display continues to be demanded. The PSA methodcan provide significant advantages here. In particular in the case ofPS-VA, PS-IPS, PS—FFS and PS-posi-VA displays, a shortening of theresponse times, which correlate with a measurable pretilt in test cells,can be achieved without significant adverse effects on other parameters.

Prior art has suggested biphenyl diacrylates or dimethacrylates, whichare optionally fluorinated as RMs for use in PSA displays

However, the problem arises that not all combinations consisting of anLC mixture and one or more RMs are suitable for use in PSA displaysbecause, for example, an inadequate tilt or none at all becomesestablished or since, for example, the so-called “voltage holding ratio”(VHR or HR) is inadequate for TFT display applications. In addition, ithas been found that, on use in PSA displays, the LC mixtures and RMsknown from the prior art do still have some disadvantages. Thus, notevery known RM which is soluble in LC mixtures is suitable for use inPSA displays. In addition, it is often difficult to find a suitableselection criterion for the RM besides direct measurement of the pretiltin the PSA display. The choice of suitable RMs becomes even smaller ifpolymerization by means of UV light without the addition ofphotoinitiators is desired, which may be advantageous for certainapplications.

In addition, the selected combination of LC host mixture/RM should havethe lowest possible rotational viscosity and the best possibleelectrical properties. In particular, it should have the highestpossible VHR. In PSA displays, a high VHR after irradiation with UVlight is particularly necessary since UV exposure is a requisite part ofthe display production process, but also occurs as normal exposureduring operation of the finished display.

In particular, it would be desirable to have available novel materialsfor PSA displays which produce a particularly small pretilt angle.Preferred materials here are those which produce a lower pretilt angleduring polymerization for the same exposure time than the materialsknown to date, and/or through the use of which the (higher) pretiltangle that can be achieved with known materials can already be achievedafter a shorter exposure time. The production time (“tact time”) of thedisplay could thus be shortened and the costs of the production processreduced.

A further problem in the production of PSA displays is the presence orremoval of residual amounts of unpolymerized RMs, in particular afterthe polymerization step for production of the pretilt angle in thedisplay. For example, unreacted RMs of this type may adversely affectthe properties of the display by, for example, polymerising in anuncontrolled manner during operation after finishing of the display.

Thus, the PSA displays known from the prior art often exhibit theundesired effect of so-called “image sticking” or “image burn”, i.e. theimage produced in the LC display by temporary addressing of individualpixels still remains visible even after the electric field in thesepixels has been switched off or after other pixels have been addressed.

This “image sticking” can occur on the one hand if LC host mixtureshaving a low VHR are used. The UV component of daylight or thebacklighting can cause undesired decomposition reactions of the LCmolecules therein and thus initiate the production of ionic orfree-radical impurities. These may accumulate, in particular, at theelectrodes or the alignment layers, where they may reduce the effectiveapplied voltage. This effect can also be observed in conventional LCdisplays without a polymer component.

In addition, an additional “image sticking” effect caused by thepresence of unpolymerized RMs is often observed in PSA displays.Uncontrolled polymerization of the residual RMs is initiated here by UVlight from the environment or by the backlighting. In the switcheddisplay areas, this changes the tilt angle after a number of addressingcycles. As a result, a change in transmission in the switched areas mayoccur, while it remains unchanged in the unswitched areas.

It is therefore desirable for the polymerization of the RMs to proceedas completely as possible during production of the PSA display and forthe presence of unpolymerized RMs in the display to be excluded as faras possible or reduced to a minimum. Thus, RMs and LC mixtures arerequired which enable or support highly effective and completepolymerization of the RMs. In addition, controlled reaction of theresidual RM amounts would be desirable. This would be simpler if the RMpolymerized more rapidly and effectively than the compounds known todate.

A further problem that has been observed in the operation of PSAdisplays is the stability of the pretilt angle. Thus, it was observedthat the pretilt angle, which was generated during display manufactureby polymerising the RM as described above, does not remain constant butcan deteriorate after the display was subjected to voltage stress duringits operation. This can negatively affect the display performance, e.g.by increasing the black state transmission and hence lowering thecontrast.

Another problem to be solved is that the RMs of prior art do often havehigh melting points, and do only show limited solubility in manycurrently common LC mixtures, and therefore frequently tend tospontaneously crystallise out of the mixture. In addition, the risk ofspontaneous polymerization prevents the LC host mixture being warmed inorder to dissolve the polymerizable component, meaning that the bestpossible solubility even at room temperature is necessary. In addition,there is a risk of separation, for example on introduction of the LCmedium into the LC display (chromatography effect), which may greatlyimpair the homogeneity of the display. This is further increased by thefact that the LC media are usually introduced at low temperatures inorder to reduce the risk of spontaneous polymerization (see above),which in turn has an adverse effect on the solubility.

Another problem observed in prior art is that the use of conventional LCmedia in LC displays, including but not limited to displays of the PSAtype, often leads to the occurrence of mura in the display, especiallywhen the LC medium is filled in the display cell manufactured using theone drop filling (ODF) method. This phenomenon is also known as “ODFmura”. It is therefore desirable to provide LC media which lead toreduced ODF mura.

Another problem observed in prior art is that LC media for use in PSAdisplays, including but not limited to displays of the PSA type, dooften exhibit high viscosities and, as a consequence, high switchingtimes. In order to reduce the viscosity and switching time of the LCmedium, it has been suggested in prior art to add LC compounds with analkenyl group. However, it was observed that LC media containing alkenylcompounds often show a decrease of the reliability and stability, and adecrease of the VHR especially after exposure to UV radiation.Especially for use in PSA displays this is a considerable disadvantage,because the photo-polymerization of the RMs in the PSA display isusually carried out by exposure to UV radiation, which may cause a VHRdrop in the LC medium.

There is thus still a great demand for PSA displays and LC media andpolymerizable compounds for use in such displays, which do not show thedrawbacks as described above, or only do so to a small extent, and haveimproved properties.

In particular, there is a great demand for PSA displays, and LC mediaand polymerizable compounds for use in such PSA displays, which enable ahigh specific resistance at the same time as a large working-temperaturerange, short response times, even at low temperatures, and a lowthreshold voltage, a low pretilt angle, a multiplicity of grey shades,high contrast and a broad viewing angle, have high reliability and highvalues for the “voltage holding ratio” (VHR) after UV exposure, and, incase of the polymerizable compounds, have low melting points and a highsolubility in the LC host mixtures. In PSA displays for mobileapplications, it is especially desired to have available LC media thatshow low threshold voltage and high birefringence.

The invention is provides novel suitable materials, in particular RMsand LC media comprising the same, for use in PSA displays, which do nothave the disadvantages indicated above or do so to a reduced extent.

In particular, the invention provides RMs, and LC media comprising them,for use in PSA displays, which enable very high specific resistancevalues, high VHR values, high reliability, low threshold voltages, shortresponse times, high birefringence, show good UV absorption especiallyat longer wavelengths, enable quick and complete polymerization of theRMs, allow the generation of a low pretilt angle as quickly as possible,enable a high stability of the pretilt even after longer time and/orafter UV exposure, reduce or prevent the occurrence of “image sticking”and “ODF mura” in the display, and in case of the RMs polymerize asrapidly and completely as possible and show a high solubility in the LCmedia which are typically used as host mixtures in PSA displays.

The invention also provides RMs, in particular for optical,electro-optical and electronic applications, and suitable processes andintermediates for the preparation thereof.

In particular, it has been found, surprisingly, that, the use of RMs offormula I as described hereinafter allows achieving the advantageouseffects as mentioned above. These compounds are characterized in thatthey have a meta-terphenyl mesogenic core to which two or more reactivegroups are attached to the outer benzene rings, but not on the centralring, and wherein at least one of these reactive groups is attached tothe benzene ring directly, and at least one of these reactive groups isattached to the benzene ring via a spacer group.

It was surprisingly found that the use of these RMs, and of LC mediacomprising them, in PSA displays facilitates a quick and completeUV-photopolymerization reaction in particular at longer UV wavelengthsin the range from 300-380 nm and especially above 340 nm, even withoutthe addition of photoinitiator, leads to a fast generation of a largeand stable pretilt angle, reduces image sticking and ODF mura in thedisplay, leads to a high reliability and a high VHR value after UVphotopolymerization, especially in case of LC host mixtures containingLC compounds with an alkenyl group, and enables to achieve fast responsetimes, a low threshold voltage and a high birefringence.

In addition, the RMs according to the invention have low melting points,good solubility in a wide range of LC media, especially in commerciallyavailable LC host mixtures for PSA use, and a low tendency tocrystallisation. Besides, they show good absorption at longer UVwavelengths, in particular in the range from 300-380 nm, and enable aquick and complete polymerization with small amounts of residual,unreacted RMs in the cell.

WO 2010/131600 A1 discloses polymerizable compounds with ameta-terphenyl structure and their use in PSA displays, but does neitherdisclose nor suggest polymerizable compounds as disclosed and claimedhereinafter.

SUMMARY OF THE INVENTION

The invention relates to polymerizable compounds of formula I

in which the individual radicals have the following meanings

-   R denotes P-Sp^(b)-, H or has one of the meanings given for L,-   Sp^(a), Sp^(b) denote, on each occurrence identically or    differently, a spacer group or a single bond,-   P denotes, on each occurrence identically or differently, a    polymerizable group,-   L F, Cl, CN, or straight chain, branched or cyclic alkyl having 1 to    25 C atoms, wherein one or more non-adjacent CH₂-groups are    optionally replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— in    such a manner that O- and/or S-atoms are not directly connected with    each other, and wherein one or more H atoms are each optionally    replaced by F or Cl,-   r is 0, 1, 2, 3 or 4,-   s is 0, 1, 2 or 3,    wherein at least one of Sp^(a) and Sp^(b) is a single bond and at    least one of Sp^(a) and Sp^(b) is different from a single bond.

The invention further relates to the use of compounds of formula I aspolymerizable compounds in LC media and LC displays, especially in theLC medium, active layer or alignment layer of an LC display, wherein theLC displays are preferably PSA displays.

The invention further relates to methods for preparing compounds offormula I, and to novel intermediates used or obtained in these methods.

The invention furthermore relates to an LC medium comprising one or morecompounds of formula I.

The invention furthermore relates to an LC medium comprising one or morepolymerizable compounds, at least one of which is a compound of formulaI.

The invention furthermore relates to an LC medium comprising

-   -   a polymerizable component A) comprising, preferably consisting        of, one or more polymerizable compounds, at least one of which        is a compound of formula I, and    -   a liquid-crystalline component B), hereinafter also referred to        as “LC host mixture”, comprising, preferably consisting of, one        or more mesogenic or liquid-crystalline compounds.

The liquid-crystalline component B) of an LC medium according to thepresent invention is hereinafter also referred to as “LC host mixture”,and preferably comprises one or more, preferably at least two mesogenicor LC compounds selected from low-molecular-weight compounds which areunpolymerizable.

The invention furthermore relates to an LC medium as described above andbelow, wherein the LC host mixture or component B) comprises at leastone mesogenic or LC compound comprising an alkenyl group.

The invention furthermore relates to an LC medium or LC display asdescribed above, wherein the compounds of formula I, or thepolymerizable compounds of component A), are polymerized.

The invention furthermore relates to a process for preparing an LCmedium as described above and below, comprising the steps of mixing oneor more mesogenic or LC compounds, or an LC host mixture or LC componentB) as described above and below, with one or more compounds of formulaI, and optionally with further LC compounds and/or additives.

The invention furthermore relates to the use of compounds of formula Iand LC media according to the invention in PSA displays, in particularthe use in PSA displays containing an LC medium, for the production of atilt angle in the LC medium by in-situ polymerization of the compound(s)of the formula I in the PSA display, preferably in an electric ormagnetic field.

The invention furthermore relates to an LC display comprising one ormore compounds of formula I or an LC medium according to the invention,in particular a PSA display, particularly preferably a PS-VA, PS-OCB,PS-IPS, PS-FFS, PS-UB-FFS, PS-posi-VA or PS-TN display.

The invention furthermore relates to an LC display comprising a polymerobtainable by polymerization of one or more compounds of formula I or ofa polymerizable component A) as described above, or comprising an LCmedium according to the invention, which is preferably a PSA display,very preferably a PS-VA, PS-OCB, PS-IPS, PS-FFS, PS-UB-FFS, PS-posi-VAor PS-TN display.

The invention furthermore relates to an LC display of the PSA typecomprising two substrates, at least one which is transparent to light,an electrode provided on each substrate or two electrodes provided ononly one of the substrates, and located between the substrates a layerof an LC medium that comprises one or more polymerizable compounds andan LC component as described above and below, wherein the polymerizablecompounds are polymerized between the substrates of the display.

The invention furthermore relates to a process for manufacturing an LCdisplay as described above and below, comprising the steps of filling orotherwise providing an LC medium, which comprises one or morepolymerizable compounds as described above and below, between thesubstrates of the display, and polymerising the polymerizable compounds.

The PSA displays according to the invention have two electrodes,preferably in the form of transparent layers, which are applied to oneor both of the substrates. In some displays, for example in PS-VA,PS-OCB or PS-TN displays, one electrode is applied to each of the twosubstrates. In other displays, for example in PS-posi-VA, PS-IPS orPS-FFS or PS-UB-FFS displays, both electrodes are applied to only one ofthe two substrates.

In a preferred embodiment the polymerizable component is polymerized inthe LC display while a voltage is applied to the electrodes of thedisplay. The polymerizable compounds of the polymerizable component arepreferably polymerized by photo-polymerization, very preferably by UVphoto-polymerization.

DETAILED DESCRIPTION OF THE INVENTION

Unless stated otherwise, the compounds of formula I are preferablyselected from achiral compounds.

As used herein, the terms “active layer” and “switchable layer” mean alayer in an electrooptical display, for example an LC display, thatcomprises one or more molecules having structural and opticalanisotropy, like for example LC molecules, which change theirorientation upon an external stimulus like an electric or magneticfield, resulting in a change of the transmission of the layer forpolarized or unpolarized light.

As used herein, the terms “tilt” and “tilt angle” will be understood tomean a tilted alignment of the LC molecules of an LC medium relative tothe surfaces of the cell in an LC display (here preferably a PSAdisplay). The tilt angle here denotes the average angle (<90°) betweenthe longitudinal molecular axes of the LC molecules (LC director) andthe surface of the plane-parallel outer plates which form the LC cell. Alow value for the tilt angle (i.e. a large deviation from the 90° angle)corresponds to a large tilt here. A suitable method for measurement ofthe tilt angle is given in the examples. Unless indicated otherwise,tilt angle values disclosed above and below relate to this measurementmethod.

As used herein, the terms “reactive mesogen” and “RM” will be understoodto mean a compound containing a mesogenic or liquid crystallineskeleton, and one or more functional groups attached thereto which aresuitable for polymerization and are also referred to as “polymerizablegroup” or “P”.

Unless stated otherwise, the term “polymerizable compound” as usedherein will be understood to mean a polymerizable monomeric compound.

As used herein, the term “low-molecular-weight compound” will beunderstood to mean to a compound that is monomeric and/or is notprepared by a polymerization reaction, as opposed to a “polymericcompound” or a “polymer”.

As used herein, the term “unpolymerizable compound” will be understoodto mean a compound that does not contain a functional group that issuitable for polymerization under the conditions usually applied for thepolymerization of the RMs.

The term “mesogenic group” as used herein is known to the person skilledin the art and described in the literature, and means a group which, dueto the anisotropy of its attracting and repelling interactions,essentially contributes to causing a liquid-crystal (LC) phase inlow-molecular-weight or polymeric substances. Compounds containingmesogenic groups (mesogenic compounds) do not necessarily have to havean LC phase themselves. It is also possible for mesogenic compounds toexhibit LC phase behaviour only after mixing with other compounds and/orafter polymerization. Typical mesogenic groups are, for example, rigidrod- or disc-shaped units. An overview of the terms and definitions usedin connection with mesogenic or LC compounds is given in Pure Appl.Chem. 2001, 73(5), 888 and C. Tschierske, G. Pelzl, S. Diele, Angew.Chem. 2004, 116, 6340-6368.

The term “spacer group”, hereinafter also referred to as “Sp”, as usedherein is known to the person skilled in the art and is described in theliterature, see, for example, Pure Appl. Chem. 2001, 73(5), 888 and C.Tschierske, G. Pelzl, S. Diele, Angew. Chem. 2004, 116, 6340-6368. Asused herein, the terms “spacer group” or “spacer” mean a flexible group,for example an alkylene group, which connects the mesogenic group andthe polymerizable group(s) in a polymerizable mesogenic compound.

Above and below,

denotes a trans-1,4-cyclohexylene ring, and

denotes a 1,4-phenylene ring.

Above and below “organic group” denotes a carbon or hydrocarbon group.

“Carbon group” denotes a mono- or polyvalent organic group containing atleast one carbon atom, where this either contains no further atoms (suchas, for example, —C≡C—) or optionally contains one or more furtheratoms, such as, for example, N, O, S, B, P, Si, Se, As, Te or Ge (forexample carbonyl, etc.). The term “hydrocarbon group” denotes a carbongroup which additionally contains one or more H atoms and optionally oneor more heteroatoms, such as, for example, N, O, S, B, P, Si, Se, As, Teor Ge.

“Halogen” denotes F, Cl, Br or I.

—CO—, —C(═O)— and —C(O)— denote a carbonyl group, i.e.

A carbon or hydrocarbon group can be a saturated or unsaturated group.Unsaturated groups are, for example, aryl, alkenyl or alkynyl groups. Acarbon or hydrocarbon radical having more than 3 C atoms can bestraight-chain, branched and/or cyclic and may also contain spiro linksor condensed rings.

The terms “alkyl”, “aryl”, “heteroaryl”, etc., also encompass polyvalentgroups, for example alkylene, arylene, heteroarylene, etc.

The term “aryl” denotes an aromatic carbon group or a group derivedtherefrom. The term “heteroaryl” denotes “aryl” as defined above,containing one or more heteroatoms, preferably selected from N, O, S,Se, Te, Si and Ge.

Preferred carbon and hydrocarbon groups are optionally substituted,straight-chain, branched or cyclic, alkyl, alkenyl, alkynyl, alkoxy,alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxy and alkoxycarbonyloxyhaving 1 to 40, preferably 1 to 20, very preferably 1 to 12, C atoms,optionally substituted aryl or aryloxy having 5 to 30, preferably 6 to25, C atoms, or optionally substituted alkylaryl, arylalkyl,alkylaryloxy, arylalkyloxy, arylcarbonyl, aryloxycarbonyl,arylcarbonyloxy and aryloxycarbonyloxy having 5 to 30, preferably 6 to25, C atoms, wherein one or more C atoms may also be replaced by heteroatoms, preferably selected from N, O, S, Se, Te, Si and Ge.

Further preferred carbon and hydrocarbon groups are C₁-C₂₀ alkyl, C₂-C₂₀alkenyl, C₂-C₂₀ alkynyl, C₃-C₂₀ allyl, C₄-C₂₀ alkyldienyl, C₄-C₂₀polyenyl, C₆-C₂₀ cycloalkyl, C₄-C₁₅ cycloalkenyl, C₆-C₃₀ aryl, C₆-C₃₀alkylaryl, C₆-C₃₀ arylalkyl, C₆-C₃₀ alkylaryloxy, C₆-C₃₀ arylalkyloxy,C₂-C₃₀ heteroaryl, C₂-C₃₀ heteroaryloxy.

Particular preference is given to C₁-C₁₂ alkyl, C₂-C₁₂ alkenyl, C₂-C₁₂alkynyl, C₆-C₂₅ aryl and C₂-C₂₅ heteroaryl.

Further preferred carbon and hydrocarbon groups are straight-chain,branched or cyclic alkyl having 1 to 20, preferably 1 to 12, C atoms,which are unsubstituted or mono- or polysubstituted by F, Cl, Br, I orCN and in which one or more non-adjacent CH₂ groups may each bereplaced, independently of one another, by —C(R^(x))═C(R^(x))—, —C≡C—,—N(R^(x))—, —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— in such a way thatO and/or S atoms are not linked directly to one another.

R^(x) preferably denotes H, F, Cl, CN, a straight-chain, branched orcyclic alkyl chain having 1 to 25 C atoms, in which, in addition, one ormore non-adjacent C atoms may be replaced by —O—, —S—, —CO—, —CO—O—,—O—CO—, —O—CO—O— and in which one or more H atoms may be replaced by For Cl, or denotes an optionally substituted aryl or aryloxy group with 6to 30 C atoms, or an optionally substituted heteroaryl or heteroaryloxygroup with 2 to 30 C atoms.

Preferred alkyl groups are, for example, methyl, ethyl, n-propyl,isopropyl, n-butyl, isobutyl, s-butyl, t-butyl, 2-methylbutyl, n-pentyl,s-pentyl, cyclopentyl, n-hexyl, cyclohexyl, 2-ethylhexyl, n-heptyl,cycloheptyl, n-octyl, cyclooctyl, n-nonyl, n-decyl, n-undecyl,n-dodecyl, dodecanyl, trifluoromethyl, perfluoro-n-butyl,2,2,2-trifluoroethyl, perfluorooctyl, perfluorohexyl, etc.

Preferred alkenyl groups are, for example, ethenyl, propenyl, butenyl,pentenyl, cyclopentenyl, hexenyl, cyclohexenyl, heptenyl, cycloheptenyl,octenyl, cyclooctenyl, etc.

Preferred alkynyl groups are, for example, ethynyl, propynyl, butynyl,pentynyl, hexynyl, octynyl, etc.

Preferred alkoxy groups are, for example, methoxy, ethoxy,2-methoxyethoxy, n-propoxy, i-propoxy, n-butoxy, i-butoxy, s-butoxy,t-butoxy, 2-methylbutoxy, n-pentoxy, n-hexoxy, n-heptoxy, n-octoxy,n-nonoxy, n-decoxy, n-undecoxy, n-dodecoxy, etc.

Preferred amino groups are, for example, dimethylamino, methylamino,methylphenylamino, phenylamino, etc.

Aryl and heteroaryl groups can be monocyclic or polycyclic, i.e. theycan contain one ring (such as, for example, phenyl) or two or morerings, which may also be fused (such as, for example, naphthyl) orcovalently bonded (such as, for example, biphenyl), or contain acombination of fused and linked rings. Heteroaryl groups contain one ormore heteroatoms, preferably selected from O, N, S and Se.

Particular preference is given to mono-, bi- or tricyclic aryl groupshaving 6 to 25 C atoms and mono-, bi- or tricyclic heteroaryl groupshaving 5 to 25 ring atoms, which optionally contain fused rings and areoptionally substituted. Preference is furthermore given to 5-, 6- or7-membered aryl and heteroaryl groups, in which, in addition, one ormore CH groups may be replaced by N, S or O in such a way that O atomsand/or S atoms are not linked directly to one another.

Preferred aryl groups are, for example, phenyl, biphenyl, terphenyl,[1,1′:3′,1″]terphenyl-2′-yl, naphthyl, anthracene, binaphthyl,phenanthrene, 9,10-dihydro-phenanthrene, pyrene, dihydropyrene,chrysene, perylene, tetracene, pentacene, benzopyrene, fluorene, indene,indenofluorene, spirobifluorene, etc.

Preferred heteroaryl groups are, for example, 5-membered rings, such aspyrrole, pyrazole, imidazole, 1,2,3-triazole, 1,2,4-triazole, tetrazole,furan, thiophene, selenophene, oxazole, isoxazole, 1,2-thiazole,1,3-thiazole, 1,2,3-oxadiazole, 1,2,4-oxadiazole, 1,2,5-oxadiazole,1,3,4-oxadiazole, 1,2,3-thiadiazole, 1,2,4-thiadiazole,1,2,5-thiadiazole, 1,3,4-thiadiazole, 6-membered rings, such aspyridine, pyridazine, pyrimidine, pyrazine, 1,3,5-triazine,1,2,4-triazine, 1,2,3-triazine, 1,2,4,5-tetrazine, 1,2,3,4-tetrazine,1,2,3,5-tetrazine, or condensed groups, such as indole, isoindole,indolizine, indazole, benzimidazole, benzotriazole, purine,naphthimidazole, phenanthrimidazole, pyridimidazole, pyrazinimidazole,quinoxalinimidazole, benzoxazole, naphthoxazole, anthroxazole,phenanthroxazole, isoxazole, benzothiazole, benzofuran, isobenzofuran,dibenzofuran, quinoline, isoquinoline, pteridine, benzo-5,6-quinoline,benzo-6,7-quinoline, benzo-7,8-quinoline, benzoisoquinoline, acridine,phenothiazine, phenoxazine, benzopyridazine, benzopyrimidine,quinoxaline, phenazine, naphthyridine, azacarbazole, benzocarboline,phenanthridine, phenanthroline, thieno[2,3b]thiophene,thieno[3,2b]thiophene, dithienothiophene, isobenzothiophene,dibenzothiophene, benzothiadiazothiophene, or combinations of thesegroups.

The aryl and heteroaryl groups mentioned above and below may also besubstituted by alkyl, alkoxy, thioalkyl, fluorine, fluoroalkyl orfurther aryl or heteroaryl groups.

The (non-aromatic) alicyclic and heterocyclic groups encompass bothsaturated rings, i.e. those containing exclusively single bonds, andalso partially unsaturated rings, i.e. those which may also containmultiple bonds. Heterocyclic rings contain one or more heteroatoms,preferably selected from Si, O, N, S and Se.

The (non-aromatic) alicyclic and heterocyclic groups can be monocyclic,i.e. contain only one ring (such as, for example, cyclohexane), orpolycyclic, i.e. contain a plurality of rings (such as, for example,decahydronaphthalene or bicyclooctane). Particular preference is givento saturated groups. Preference is furthermore given to mono-, bi- ortricyclic groups having 5 to 25 ring atoms, which optionally containfused rings and are optionally substituted. Preference is furthermoregiven to 5-, 6-, 7- or 8-membered carbocyclic groups, in which, inaddition, one or more C atoms may be replaced by Si and/or one or moreCH groups may be replaced by N and/or one or more non-adjacent CH₂groups may be replaced by —O— and/or —S—.

Preferred alicyclic and heterocyclic groups are, for example, 5-memberedgroups, such as cyclopentane, tetrahydrofuran, tetrahydrothiofuran,pyrrolidine, 6-membered groups, such as cyclohexane, silinane,cyclohexene, tetrahydropyran, tetrahydrothiopyran, 1,3-dioxane,1,3-dithiane, piperidine, 7-membered groups, such as cycloheptane, andfused groups, such as tetrahydronaphthalene, decahydronaphthalene,indane, bicyclo[1.1.1]-pentane-1,3-diyl, bicyclo[2.2.2]octane-1,4-diyl,spiro[3.3]heptane-2,6-diyl, octahydro-4,7-methanoindane-2,5-diyl.

Preferred substituents are, for example, solubility-promoting groups,such as alkyl or alkoxy, electron-withdrawing groups, such as fluorine,nitro or nitrile, or substituents for increasing the glass transitiontemperature (Tg) in the polymer, in particular bulky groups, such as,for example, t-butyl or optionally substituted aryl groups.

Preferred substituents, hereinafter also referred to as “L”, are, forexample, F, Cl, Br, I, —CN, —NO₂, —NCO, —NCS, —OCN, —SCN,—C(═O)N(R^(x))₂, —C(═O)Y¹, —C(═O)R^(x), —N(R^(x))₂, straight-chain orbranched alkyl, alkoxy, alkylcarbonyl, alkoxycarbonyl, alkylcarbonyloxyor alkoxycarbonyloxy each having 1 to 25 C atoms, in which one or more Hatoms may optionally be replaced by F or Cl, optionally substitutedsilyl having 1 to 20 Si atoms, or optionally substituted aryl having 6to 25, preferably 6 to 15, C atoms,

wherein R^(x) denotes H, F, Cl, CN, or straight chain, branched orcyclic alkyl having 1 to 25 C atoms, wherein one or more non-adjacentCH₂-groups are optionally replaced by —O—, —S—, —CO—, —CO—O—, —O—CO—,—O—CO—O— in such a manner that O- and/or S-atoms are not directlyconnected with each other, and wherein one or more H atoms are eachoptionally replaced by F, Cl, P— or P-Sp-, andY¹ denotes halogen.

“Substituted silyl or aryl” preferably means substituted by halogen,—CN, R⁰, —OR⁰, —CO—R⁰, —CO—O—R⁰, —O—CO—R⁰ or —O—CO—O—R⁰, wherein R⁰denotes H or alkyl with 1 to 20 C atoms.

Particularly preferred substituents L are, for example, F, Cl, CN, NO₂,CH₃, C₂H₅, OCH₃, OC₂H₅, COCH₃, COC₂H₅, COOCH₃, COOC₂H₅, CF₃, OCF₃,OCHF₂, OC₂F₅, furthermore phenyl.

is preferably

in which L has one of the meanings indicated above.

The polymerizable group P is a group which is suitable for apolymerization reaction, such as, for example, free-radical or ionicchain polymerization, polyaddition or polycondensation, or for apolymer-analogous reaction, for example addition or condensation onto amain polymer chain. Particular preference is given to groups for chainpolymerization, in particular those containing a C═C double bond or—C≡C— triple bond, and groups which are suitable for polymerization withring opening, such as, for example, oxetane or epoxide groups.

Preferred groups P are selected from the group consisting ofCH₂═CW¹—CO—O—, CH₂═CW¹—CO—,

CH₂═CW²—(O)_(k3)—, CW¹═CH—CO—(O)_(k3)—, CW¹═CH—CO—NH—, CH₂═CW¹—CO—NH—,CH₃—CH═CH—O—, (CH₂═CH)₂CH—OCO—, (CH₂═CH—CH₂)₂CH—OCO—, (CH₂═CH)₂CH—O—,(CH₂═CH—CH₂)₂N—, (CH₂═CH—CH₂)₂N—CO—, HO—CW²W³—, HS—CW²W³—, HW²N—,HO—CW²W³—NH—, CH₂═CW¹—CO—NH—, CH₂═CH—(COO)_(k1)-Phe-(O)_(k2)—,CH₂═CH—(CO)_(k1)-Phe-(O)_(k2)—, Phe-CH═CH—, HOOC—, OCN— and W⁴W⁵W⁶Si—,in which W¹ denotes H, F, Cl, CN, CF₃, phenyl or alkyl having 1 to 5 Catoms, in particular H, F, Cl or CH₃, W² and W³ each, independently ofone another, denote H or alkyl having 1 to 5 C atoms, in particular H,methyl, ethyl or n-propyl, W⁴, W⁵ and W⁶ each, independently of oneanother, denote Cl, oxaalkyl or oxacarbonylalkyl having 1 to 5 C atoms,W⁷ and W⁸ each, independently of one another, denote H, Cl or alkylhaving 1 to 5 C atoms, Phe denotes 1,4-phenylene, which is optionallysubstituted by one or more radicals L as defined above which are otherthan P-Sp-, k₁, k₂ and k₃ each, independently of one another, denote 0or 1, k₃ preferably denotes 1, and k₄ denotes an integer from 1 to 10.

Very preferred groups P are selected from the group consisting ofCH₂═CW¹—CO—O—, CH₂═CW¹—CO—,

CH₂═CW²—O—, CH₂═CW²—, CW¹═CH—CO—(O)_(k3)—, CW¹═CH—CO—NH—,CH₂═CW¹—CO—NH—, (CH₂═CH)₂CH—OCO—, (CH₂═CH—CH₂)₂CH—OCO—, (CH₂═CH)₂CH—O—,(CH₂═CH—CH₂)₂N—, (CH₂═CH—CH₂)₂N—CO—, CH₂═CW¹—CO—NH—,CH₂═CH—(COO)_(k1)-Phe-(O)_(k2)—, CH₂═CH—(CO)_(k1)-Phe-(O)_(k2)—,Phe-CH═CH— and W⁴W⁵W⁶Si—, in which W¹ denotes H, F, Cl, CN, CF₃, phenylor alkyl having 1 to 5 C atoms, in particular H, F, Cl or CH₃, W² and W³each, independently of one another, denote H or alkyl having 1 to 5 Catoms, in particular H, methyl, ethyl or n-propyl, W⁴, W⁵ and W⁶ each,independently of one another, denote Cl, oxaalkyl or oxacarbonylalkylhaving 1 to 5 C atoms, W⁷ and W⁸ each, independently of one another,denote H, Cl or alkyl having 1 to 5 C atoms, Phe denotes 1,4-phenylene,k₁, k₂ and k₃ each, independently of one another, denote 0 or 1, k₃preferably denotes 1, and k₄ denotes an integer from 1 to 10.

Very particularly preferred groups P are selected from the groupconsisting of CH₂═CW¹—CO—O—, in particular CH₂═CH—CO—O—,CH₂═C(CH₃)—CO—O— and CH₂═CF—CO—O—, furthermore CH₂═CH—O—,(CH₂═CH)₂CH—O—CO—, (CH₂═CH)₂CH—O—,

Further preferred polymerizable groups P are selected from the groupconsisting of vinyloxy, acrylate, methacrylate, fluoroacrylate,chloroacrylate, oxetane and epoxide, most preferably from acrylate andmethacrylate.

If the spacer group Sp^(a,b) is different from a single bond, it ispreferably of the formula Sp″-X″, so that the respective radicalP-Sp^(a,b)- conforms to the formula P-Sp″-X″—, wherein

-   Sp″ denotes alkylene having 1 to 20, preferably 1 to 12, C atoms,    which is optionally mono- or polysubstituted by F, Cl, Br, I or CN    and in which, in addition, one or more non-adjacent CH₂ groups may    each be replaced, independently of one another, by —O—, —S—, —NH—,    —N(R⁰)—, —Si(R⁰R⁰⁰)—, —CO—, —CO—O—, —O—CO—, —O—CO—O—, —S—CO—,    —CO—S—, —N(R⁰⁰)—CO—O—, —O—CO—N(R⁰)—, —N(R⁰)—CO—N(R⁰⁰)—, —CH═CH— or    —C≡C— in such a way that O and/or S atoms are not linked directly to    one another,-   X″ denotes —O—, —S—, —CO—, —CO—O—, —O—CO—, —O—CO—O—, —CO—N(R⁰)—,    —N(R⁰)—CO—, —N(R⁰)—CO—N(R⁰⁰)—, —OCH₂—, —CH₂O—, —SCH₂—, —CH₂S—,    —CF₂O—, —OCF₂—, —CF₂S—, —SCF₂—, —CF₂CH₂—, —CH₂CF₂—, —CF₂CF₂—,    —CH═N—, —N═CH—, —N═N—, —CH═CR⁰—, —CY²═CY³—, —C≡C—, —CH═CH—CO—O—,    —O—CO—CH═CH— or a single bond,-   R⁰ and R⁰⁰ each, independently of one another, denote H or alkyl    having 1 to 20 C atoms, and-   Y² and Y³ each, independently of one another, denote H, F, Cl or CN.-   X″ is preferably —O—, —S—, —CO—, —COO—, —COO—, —O—COO—, —CO—NR⁰—,    —NR⁰—CO—, —NR⁰—CO—NR⁰⁰— or a single bond.

Typical spacer groups Sp and -Sp″-X″— are, for example, —(CH₂)_(p1)—,—(CH₂CH₂O)_(q1)—CH₂CH₂—, —CH₂CH₂—S—CH₂CH₂—, —CH₂CH₂—NH—CH₂CH₂— or—(SiR⁰R⁰⁰—O)_(p1)—, in which p1 is an integer from 1 to 12, q1 is aninteger from 1 to 3, and R⁰ and R⁰⁰ have the meanings indicated above.

Particularly preferred groups Sp^(a,b) and -Sp″-X″— are —(CH₂)_(p1)—,—(CH₂)_(p1)—O—, —(CH₂)_(p1)—O—CO—, —(CH₂)_(p1)—CO—O—,—(CH₂)_(p1)—O—CO—O—, in which p1 and q1 have the meanings indicatedabove.

Particularly preferred groups Sp″ are, in each case straight-chain,ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene,nonylene, decylene, undecylene, dodecylene, octadecylene,ethyleneoxyethylene, methyleneoxybutylene, ethylenethioethylene,ethylene-N-methyliminoethylene, 1-methylalkylene, ethenylene,propenylene and butenylene.

In formula I R preferably denotes H or P-Sp^(b).

Preferred compounds of formula I are selected from the followingsubformulae

wherein P, Sp^(a), Sp^(b), L and r are as defined in formula I.

Very preferred compounds of formula I are selected from the followingsubformulae:

wherein P, L and r have the meaning of formula I and Sp¹ is a spacergroup.

Further preferred compounds of formula I and its subformulae I1-I4 andI1a-I4a are selected from the following preferred embodiments, includingany combination thereof:

-   -   The compounds contain exactly three polymerizable groups        (represented by the groups P),    -   P is selected from the group consisting of acrylate,        methacrylate and oxetane,    -   Sp^(a) and Sp^(b), when being different from a single bond, and        Sp¹ are selected from —(CH₂)_(a)—, —(CH₂)_(a)—O—,        —(CH₂)_(a)—CO—O—, —(CH₂)_(a)—O—CO—, wherein a is 2, 3, 4, 5 or        6, and the O-atom or the CO-group, respectively, is connected to        the benzene ring,    -   L denotes F, Cl, CN, or alkyl or alkoxy with 1 to 6 C atoms that        is optionally fluorinated, very preferably F, Cl, CN, CH₃, OCH₃,        OCF₃, OCF₂H or OCFH₂, most preferably F,    -   r is 0 or 1,    -   s is 0.

Specific preferred compounds are selected from the following formulae

The invention furthermore relates to compounds of formula II

wherein Sp^(a), Sp^(b), L, r and s are as defined in formula I, Rdenotes H or Pg-Sp^(b), and Pg denotes OH, a protected hydroxyl group ora masked hydroxyl group.

Preferred compounds of formula II are selected from subformulae I1-I4and I1a-I4a as defined above, wherein P is replaced by Pg.

Suitable protected hydroxyl groups Pg are known to the person skilled inthe art. Preferred protecting groups for hydroxyl groups are alkyl,alkoxyalkyl, acyl, alkylsilyl, arylsilyl and arylmethyl groups,especially 2-tetrahydropyranyl, methoxymethyl, methoxyethoxymethyl,acetyl, triisopropylsilyl, tert-butyl-dimethylsilyl or benzyl.

The term “masked hydroxyl group” is understood to mean any functionalgroup that can be chemically converted into a hydroxyl group. Suitablemasked hydroxyl groups Pg are known to the person skilled in the art.

The compounds of formula II are suitable as intermediates for thepreparation of compounds of the formula I and its subformulae.

The invention further relates to the use of the compounds of formula IIas intermediates for the preparation of compounds of the formula I andits subformulae.

The compounds and intermediates of the formulae I and II andsub-formulae thereof can be prepared analogously to processes known tothe person skilled in the art and described in standard works of organicchemistry, such as, for example, in Houben-Weyl, Methoden derorganischen Chemie [Methods of Organic Chemistry], Thieme-Verlag,Stuttgart.

For example, compounds of formula I can be synthesised by esterificationor etherification of the intermediates of formula II, wherein Pg denotesOH, using corresponding acids, acid derivatives, or halogenatedcompounds containing a polymerizable group P.

For example, acrylic or methacrylic esters can be prepared byesterification of the corresponding alcohols with acid derivatives like,for example, (meth)acryloyl chloride or (meth)acrylic anhydride in thepresence of a base like pyridine or triethyl amine, and4-(N,N-dimethylamino)pyridine (DMAP). Alternatively the esters can beprepared by esterification of the alcohols with (meth)acrylic acid inthe presence of a dehydrating reagent, for example according to Steglichwith dicyclohexylcarbodiimide (DCC),N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide (EDC) orN-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride and DMAP.

Further suitable methods are shown in the Examples.

For the production of PSA displays, the polymerizable compoundscointained in the LC medium are polymerized or crosslinked (if onecompound contains two or more polymerizable groups) by in-situpolymerization in the LC medium between the substrates of the LCdisplay, optionally while a voltage is applied to the electrodes.

The structure of the PSA displays according to the invention correspondsto the usual geometry for PSA displays, as described in the prior artcited at the outset. Geometries without protrusions are preferred, inparticular those in which, in addition, the electrode on the colourfilter side is unstructured and only the electrode on the TFT side hasslots. Particularly suitable and preferred electrode structures forPS-VA displays are described, for example, in US 2006/0066793 A1.

A preferred PSA type LC display of the present invention comprises:

-   -   a first substrate including a pixel electrode defining pixel        areas, the pixel electrode being connected to a switching        element disposed in each pixel area and optionally including a        micro-slit pattern, and optionally a first alignment layer        disposed on the pixel electrode,    -   a second substrate including a common electrode layer, which may        be disposed on the entire portion of the second substrate facing        the first substrate, and optionally a second alignment layer,    -   an LC layer disposed between the first and second substrates and        including an LC medium comprising a polymerizable component A        and a liquid crystal component B as described above and below,        wherein the polymerizable component A may also be polymerized.

The first and/or second alignment layer controls the alignment directionof the LC molecules of the LC layer. For example, in PS-VA displays thealignment layer is selected such that it imparts to the LC moleculeshomeotropic (or vertical) alignment (i.e. perpendicular to the surface)or tilted alignment. Such an alignment layer may for example comprise apolyimide, which may also be rubbed, or may be prepared by aphotoalignment method.

The LC layer with the LC medium can be deposited between the substratesof the display by methods that are conventionally used by displaymanufacturers, for example the so-called one-drop-filling (ODF) method.The polymerizable component of the LC medium is then polymerized forexample by UV photopolymerization. The polymerization can be carried outin one step or in two or more steps.

The PSA display may comprise further elements, like a colour filter, ablack matrix, a passivation layer, optical retardation layers,transistor elements for addressing the individual pixels, etc., all ofwhich are well known to the person skilled in the art and can beemployed without inventive skill.

The electrode structure can be designed by the skilled person dependingon the individual display type. For example for PS-VA displays amulti-domain orientation of the LC molecules can be induced by providingelectrodes having slits and/or bumps or protrusions in order to createtwo, four or more different tilt alignment directions.

Upon polymerization the polymerizable compounds form a crosslinkedpolymer, which causes a certain pretilt of the LC molecules in the LCmedium. Without wishing to be bound to a specific theory, it is believedthat at least a part of the crosslinked polymer, which is formed by thepolymerizable compounds, will phase-separate or precipitate from the LCmedium and form a polymer layer on the substrates or electrodes, or thealignment layer provided thereon. Microscopic measurement data (like SEMand AFM) have confirmed that at least a part of the formed polymeraccumulates at the LC/substrate interface.

The polymerization can be carried out in one step. It is also possiblefirstly to carry out the polymerization, optionally while applying avoltage, in a first step in order to produce a pretilt angle, andsubsequently, in a second polymerization step without an appliedvoltage, to polymerize or crosslink the compounds which have not reactedin the first step (“end curing”).

Suitable and preferred polymerization methods are, for example, thermalor photopolymerization, preferably photopolymerization, in particular UVinduced photopolymerization, which can be achieved by exposure of thepolymerizable compounds to UV radiation.

Optionally one or more polymerization initiators are added to the LCmedium. Suitable conditions for the polymerization and suitable typesand amounts of initiators are known to the person skilled in the art andare described in the literature. Suitable for free-radicalpolymerization are, for example, the commercially availablephotoinitiators Irgacure651®, Irgacure184®, Irgacure907®, Irgacure369®or Darocure1173® (Ciba AG). If a polymerization initiator is employed,its proportion is preferably 0.001 to 5% by weight, particularlypreferably 0.001 to 1% by weight.

The polymerizable compounds according to the invention are also suitablefor polymerization without an initiator, which is accompanied byconsiderable advantages, such, for example, lower material costs and inparticular less contamination of the LC medium by possible residualamounts of the initiator or degradation products thereof. Thepolymerization can thus also be carried out without the addition of aninitiator. In a preferred embodiment, the LC medium thus does notcontain a polymerization initiator.

The the LC medium may also comprise one or more stabilisers in order toprevent undesired spontaneous polymerization of the RMs, for exampleduring storage or transport. Suitable types and amounts of stabilisersare known to the person skilled in the art and are described in theliterature. Particularly suitable are, for example, the commerciallyavailable stabilisers from the Irganox® series (Ciba AG), such as, forexample, Irganox® 1076. If stabilisers are employed, their proportion,based on the total amount of RMs or the polymerizable component(component A), is preferably 10-500,000 ppm, particularly preferably50-50,000 ppm.

The polymerizable compounds of formula I do in particular show good UVabsorption in, and are therefore especially suitable for, a process ofpreparing a PSA display including one or more of the following features:

-   -   the polymerizable medium is exposed to UV light in the display        in a 2-step process, including a first UV exposure step (“UV-1        step”) to generate the tilt angle, and a second UV exposure step        (“UV-2 step”) to finish polymerization,    -   the polymerizable medium is exposed to UV light in the display        generated by an energy-saving UV lamp (also known as “green UV        lamps”). These lamps are characterized by a relative low        intensity ( 1/100- 1/10 of a conventional UV1 lamp) in their        absorption spectra from 300-380 nm, and are preferably used in        the UV2 step, but are optionally also used in the UV1 step when        avoiding high intensity is necessary for the process.    -   the polymerizable medium is exposed to UV light in the display        generated by a UV lamp with a radiation spectrum that is shifted        to longer wavelengths, preferably 340 nm or more, to avoid short        UV light exposure in the PS-VA process.

Both using lower intensity and a UV shift to longer wavelengths protectthe organic layer against damage that may be caused by the UV light.

A preferred embodiment of the present invention relates to a process forpreparing a PSA display as described above and below, comprising one ormore of the following features:

-   -   the polymerizable LC medium is exposed to UV light in a 2-step        process, including a first UV exposure step (“UV-1 step”) to        generate the tilt angle, and a second UV exposure step (“UV-2        step”) to finish polymerization,    -   the polymerizable LC medium is exposed to UV light generated by        a UV lamp having an intensity of from 0.5 mW/cm² to 10 mW/cm² in        the wavelength range from 300-380 nm, preferably used in the UV2        step, and optionally also in the UV1 step,    -   the polymerizable LC medium is exposed to UV light having a        wavelength of 340 nm or more, and preferably 400 nm or less.

This preferred process can be carried out for example by using thedesired UV lamps or by using a band pass filter and/or a cut-off filter,which are substantially transmissive for UV light with the respectivedesired wavelength(s) and are substantially blocking light with therespective undesired wavelengths. For example, when irradiation with UVlight of wavelengths λ of 300-400 nm is desired, UV exposure can becarried out using a wide band pass filter being substantiallytransmissive for wavelengths 300 nm<λ<400 nm. When irradiation with UVlight of wavelength λ of more than 340 nm is desired, UV exposure can becarried out using a cut-off filter being substantially transmissive forwavelengths λ>340 nm.

“Substantially transmissive” means that the filter transmits asubstantial part, preferably at least 50% of the intensity, of incidentlight of the desired wavelength(s). “Substantially blocking” means thatthe filter does not transmit a substantial part, preferably at least 50%of the intensity, of incident light of the undesired wavelengths.“Desired (undesired) wavelength” e.g. in case of a band pass filtermeans the wavelengths inside (outside) the given range of λ, and in caseof a cut-off filter means the wavelengths above (below) the given valueof λ.

This preferred process enables the manufacture of displays by usinglonger UV wavelengths, thereby reducing or even avoiding the hazardousand damaging effects of short UV light components.

UV radiation energy is in general from 6 to 100 J, depending on theproduction process conditions.

Preferably the LC medium according to the present invention doesessentially consist of a polymerizable component A), or one or morepolymerizable compounds of formula I, and an LC component B), or LC hostmixture, as described above and below. However, the LC medium mayadditionally comprise one or more further components or additives,preferably selected from the list including but not limited toco-monomers, chiral dopants, polymerization initiators, inhibitors,stabilizers, surfactants, wetting agents, lubricating agents, dispersingagents, hydrophobing agents, adhesive agents, flow improvers, defoamingagents, deaerators, diluents, reactive diluents, auxiliaries,colourants, dyes, pigments and nanoparticles.

Particular preference is given to LC media comprising one, two or threepolymerizable compounds of formula I.

Preference is furthermore given to LC media in which the polymerizablecomponent A) comprises exclusively polymerizable compounds of formula I.

Preference is furthermore given to LC media in which theliquid-crystalline component B) or the LC host mixture has a nematic LCphase, and preferably has no chiral liquid crystal phase.

The LC component B), or LC host mixture, is preferably a nematic LCmixture.

Preference is furthermore given to achiral compounds of formula I, andto LC media in which the compounds of component A and/or B are selectedexclusively from the group consisting of achiral compounds.

Preferably the proportion of the polymerizable component A) in the LCmedium is from >0 to <5%, very preferably from >0 to <1%, mostpreferably from 0.01 to 0.5%.

Preferably the proportion of compounds of formula I in the LC medium isfrom >0 to <5%, very preferably from >0 to <1%, most preferably from0.01 to 0.5%.

Preferably the proportion of the LC component B) in the LC medium isfrom 95 to <100%, very preferably from 99 to <100%.

In a preferred embodiment the polymerizable compounds of thepolymerizable component B) are exclusively selected from formula I.

In another preferred embodiment the polymerizable component B)comprises, in addition to the compounds of formula I, one or morefurther polymerizable compounds (“co-monomers”), preferably selectedfrom RMs.

Suitable and preferred mesogenic comonomers are selected from thefollowing formulae:

in which the individual radicals have the following meanings:

-   P¹, P² and P³ each, independently of one another, denote an acrylate    or methacrylate group,-   Sp¹, Sp² and Sp^(a) each, independently of one another, denote a    single bond or a spacer group having one of the meanings indicated    above and below for Sp¹, and particularly preferably denote    —(CH₂)_(p1)—, —(CH₂)_(p1)—O—, —(CH₂)_(p1)—CO—O—, —(CH₂)_(p1)—O—CO—    or —(CH₂)_(p1)—O—CO—O—, in which p1 is an integer from 1 to 12,    where, in addition, one or more of the radicals P¹-Sp¹-, P¹-Sp²- and    P³-Sp³- may denote R^(aa), with the proviso that at least one of the    radicals P¹-Sp¹-, P²-Sp² and P³-Sp³- present is different from    R^(aa),-   R^(aa) denotes H, F, Cl, CN or straight-chain or branched alkyl    having 1 to 25 C atoms, in which, in addition, one or more    non-adjacent CH₂ groups may each be replaced, independently of one    another, by C(R⁰)═C(R⁰⁰)—, —C≡C—, —N(R⁰), —O—, —S—, —CO—, —CO—O—,    —O—CO—, —O—CO—O— in such a way that O and/or S atoms are not linked    directly to one another, and in which, in addition, one or more H    atoms may be replaced by F, Cl, CN or P¹-Sp¹-, particularly    preferably straight-chain or branched, optionally mono- or    polyfluorinated alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl,    alkoxycarbonyl, alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12    C atoms (where the alkenyl and alkynyl radicals have at least two C    atoms and the branched radicals have at least three C atoms),-   R⁰, R⁰⁰ each, independently of one another and identically or    differently on each occurrence, denote H or alkyl having 1 to 12 C    atoms,-   R^(y) and R^(z) each, independently of one another, denote H, F, CH₃    or CF₃,-   X¹, X² and X³ each, independently of one another, denote —CO—O—,    —O—CO— or a single bond,-   Z¹ denotes —O—, —CO—, —C(R^(y)R^(z))— or —CF₂CF₂—,-   Z² and Z³ each, independently of one another, denote —CO—O—, —O—CO—,    —CH₂O—, —OCH₂—, —CF₂O—, —OCF₂— or —(CH₂)_(n)—, where n is 2, 3 or 4,-   L on each occurrence, identically or differently, denotes F, Cl, CN    or straight-chain or branched, optionally mono- or poly-fluorinated    alkyl, alkoxy, alkenyl, alkynyl, alkylcarbonyl, alkoxycarbonyl,    alkylcarbonyloxy or alkoxycarbonyloxy having 1 to 12 C atoms,    preferably F,-   L′ and L″ each, independently of one another, denote H, F or Cl,-   r denotes 0, 1, 2, 3 or 4,-   s denotes 0, 1, 2 or 3,-   t denotes 0, 1 or 2,-   x denotes 0 or 1.

Especially preferred are compounds of formulae M2, M13, M17, M22, M23and M29.

Further preferred are trireactive compounds M15 to M30, in particularM17, M18, M19, M22, M23, M24, M25, M29 and M30.

In the compounds of formulae M1 to M30 the group

is preferably

wherein L on each occurrence, identically or differently, has one of themeanings given above or below, and is preferably F, Cl, CN, NO₂, CH₃,C₂H₅, C(CH₃)₃, CH(CH₃)₂, CH₂CH(CH₃)C₂H₅, OCH₃, OC₂H₅, COCH₃, COC₂H₅,COOCH₃, COOC₂H₅, CF₃, OCF₃, OCHF₂, OC₂F₅ or P-Sp-, very preferably F,Cl, CN, CH₃, C₂H₅, OCH₃, COCH₃, OCF₃ or P-Sp-, more preferably F, Cl,CH₃, OCH₃, COCH₃ order OCF₃, especially F or CH₃.

Besides the polymerizable compounds described above, the LC media foruse in the LC displays according to the invention comprise an LC mixture(“host mixture”) comprising one or more, preferably two or more LCcompounds which are selected from low-molecular-weight compounds thatare unpolymerizable. These LC compounds are selected such that theystable and/or unreactive to a polymerization reaction under theconditions applied to the polymerization of the polymerizable compounds.

In principle, any LC mixture which is suitable for use in conventionaldisplays is suitable as host mixture. Suitable LC mixtures are known tothe person skilled in the art and are described in the literature, forexample mixtures in VA displays in EP 1 378 557 A1 and mixtures for OCBdisplays in EP 1 306 418 A1 and DE 102 24 046 A1.

The polymerizable compounds of formula I are especially suitable for usein an LC host mixture that comprises one or more mesogenic or LCcompounds comprising an alkenyl group (hereinafter also referred to as“alkenyl compounds”), wherein said alkenyl group is stable to apolymerization reaction under the conditions used for polymerization ofthe compounds of formula I and of the other polymerizable compoundscontained in the LC medium. Compared to RMs known from prior art thecompounds of formula I do in such an LC host mixture exhibit improvedproperties, like solubility, reactivity or capability of generating atilt angle.

Thus, in addition to the polymerizable compounds of formula I, the LCmedium according to the present invention comprises one or moremesogenic or liquid crystalline compounds comprising an alkenyl group,(“alkenyl compound”), where this alkenyl group is preferably stable to apolymerization reaction under the conditions used for the polymerizationof the polymerizable compounds of formula I or of the otherpolymerizable compounds contained in the LC medium.

The alkenyl groups in the alkenyl compounds are preferably selected fromstraight-chain, branched or cyclic alkenyl, in particular having 2 to 25C atoms, particularly preferably having 2 to 12 C atoms, in which, inaddition, one or more non-adjacent CH₂ groups may be replaced by —O—,—S—, —CO—, —CO—O—, —O—CO—, —O—CO—O— in such a way that O and/or S atomsare not linked directly to one another, and in which, in addition, oneor more H atoms may be replaced by F and/or Cl.

Preferred alkenyl groups are straight-chain alkenyl having 2 to 7 Catoms and cyclohexenyl, in particular ethenyl, propenyl, butenyl,pentenyl, hexenyl, heptenyl, 1,4-cyclohexen-1-yl and1,4-cyclohexen-3-yl.

The concentration of compounds containing an alkenyl group in the LChost mixture (i.e. without any polymerizable compounds) is preferablyfrom 5% to 100%, very preferably from 20% to 60%.

Especially preferred are LC mixtures containing 1 to 5, preferably 1, 2or 3 compounds having an alkenyl group.

The mesogenic and LC compounds containing an alkenyl group arepreferably selected from the following formulae:

in which the individual radicals, on each occurrence identically ordifferently, each, independently of one another, have the followingmeaning:

-   R^(A1) alkenyl having 2 to 9 C atoms or, if at least one of the    rings X, Y and Z denotes cyclohexenyl, also one of the meanings of    R^(A2),-   R^(A2) alkyl having 1 to 12 C atoms, in which, in addition, one or    two non-adjacent CH₂ groups may be replaced by —O—, —CH═CH—, —CO—,    —OCO— or —COO— in such a way that O atoms are not linked directly to    one another,-   Z^(x) —CH₂CH₂—, —CH═CH—, —CF₂O—, —OCF₂—, —CH₂O—, —OCH₂—, —CO—O—,    —O—CO—, —C₂F₄—, —CF═CF—, —CH═CH—CH₂O—, or a single bond, preferably    a single bond,-   L¹⁻⁴ each, independently of one another, H, F, Cl, OCF₃, CF₃, CH₃,    CH₂F or CHF₂H, preferably H, F or Cl,-   x 1 or 2,-   z 0 or 1.-   R^(A2) is preferably straight-chain alkyl or alkoxy having 1 to 8 C    atoms or straight-chain alkenyl having 2 to 7 C atoms.

The LC medium preferably comprises no compounds containing a terminalvinyloxy group (—O—CH═CH₂), in particular no compounds of the formula ANor AY in which R^(A1) or R^(A2) denotes or contains a terminal vinyloxygroup (—O—CH═CH₂).

Preferably, L¹ and L² denote F, or one of L¹ and L² denotes F and theother denotes Cl, and L³ and L⁴ denote F, or one of L³ and L⁴ denotes Fand the other denotes Cl.

The compounds of the formula AN are preferably selected from thefollowing sub-formulae:

in which alkyl and alkyl* each, independently of one another, denote astraight-chain alkyl radical having 1-6 C atoms, and alkenyl andalkenyl* each, independently of one another, denote a straight-chainalkenyl radical having 2-7 C atoms. Alkenyl and alkenyl* preferablydenote CH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—, CH₃—CH₂—CH═CH—,CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— or CH₃—CH═CH—(CH₂)₂—.

Very preferred compounds of the formula AN are selected from thefollowing sub-formulae:

in which m denotes 1, 2, 3, 4, 5 or 6, i denotes 0, 1, 2 or 3, andR^(b1) denotes H, CH₃ or C₂H₅.

Very particularly preferred compounds of the formula AN are selectedfrom the following sub-formulae:

Most preferred are compounds of formula AN1a2 and AN1a5.

The compounds of the formula AY are preferably selected from thefollowing sub-formulae:

in which alkyl and alkyl* each, independently of one another, denote astraight-chain alkyl radical having 1-6 C atoms, and alkenyl andalkenyl* each, independently of one another, denote a straight-chainalkenyl radical having 2-7 C atoms. Alkenyl and alkenyl* preferablydenote CH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—, CH₃—CH₂—CH═CH—,CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— or CH₃—CH═CH—(CH₂)₂—.

Very preferred compounds of the formula AY are selected from thefollowing sub-formulae:

in which m and n each, independently of one another, denote 1, 2, 3, 4,5 or 6, and alkenyl denotes CH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—,CH₃—CH₂—CH═CH—, CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— orCH₃—CH═CH—(CH₂)₂—.

Besides the polymerizable component A) as described above, the LC mediaaccording to the present invention comprise an LC component B), or LChost mixture, comprising one or more, preferably two or more LCcompounds which are selected from low-molecular-weight compounds thatare unpolymerizable. These LC compounds are selected such that theystable and/or unreactive to a polymerization reaction under theconditions applied to the polymerization of the polymerizable compounds.

In a first preferred embodiment the LC medium contains an LC componentB), or LC host mixture, based on compounds with negative dielectricanisotropy. Such LC media are especially suitable for use in PS-VA andPS-UB-FFS displays. Particularly preferred embodiments of such an LCmedium are those of sections a)-z) below:

-   a) LC medium which comprises one or more compounds of the formulae    CY and/or PY:

-   -   wherein    -   a denotes 1 or 2,    -   b denotes 0 or 1,

denotes

-   -   R¹ and R² each, independently of one another, denote alkyl        having 1 to 12 C atoms, where, in addition, one or two        non-adjacent CH₂ groups may be replaced by —O—, —CH═CH—, —CO—,        —OCO— or —COO— in such a way that O atoms are not linked        directly to one another, preferably alkyl or alkoxy having 1 to        6 C atoms,    -   Z^(x) and Z^(y) each, independently of one another, denote        —CH₂CH₂—, —CH═CH—, —CF₂O—, —OCF₂—, —CH₂O—, —OCH₂—, —CO—O—,        —O—CO—, —C₂F₄—, —CF═CF—, —CH═CH—CH₂O— or a single bond,        preferably a single bond,    -   L¹⁻⁴ each, independently of one another, denote F, Cl, OCF₃,        CF₃, CH₃, CH₂F, CHF₂.

Preferably, both L¹ and L² denote F or one of L¹ and L² denotes F andthe other denotes Cl, or both L³ and L⁴ denote F or one of L³ and L⁴denotes F and the other denotes Cl.

The compounds of the formula CY are preferably selected from the groupconsisting of the following sub-formulae:

in which a denotes 1 or 2, alkyl and alkyl* each, independently of oneanother, denote a straight-chain alkyl radical having 1-6 C atoms, andalkenyl denotes a straight-chain alkenyl radical having 2-6 C atoms, and(O) denotes an oxygen atom or a single bond. Alkenyl preferably denotesCH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—, CH₃—CH₂—CH═CH—, CH₃—(CH₂)₂—CH═CH—,CH₃—(CH₂)₃—CH═CH— or CH₃—CH═CH—(CH₂)₂—.

The compounds of the formula PY are preferably selected from the groupconsisting of the following sub-formulae:

in which alkyl and alkyl* each, independently of one another, denote astraight-chain alkyl radical having 1-6 C atoms, and alkenyl denotes astraight-chain alkenyl radical having 2-6 C atoms, and (O) denotes anoxygen atom or a single bond. Alkenyl preferably denotes CH₂═CH—,CH₂═CHCH₂CH₂—, CH₃—CH═CH—, CH₃—CH₂—CH═CH—, CH₃—(CH₂)₂—CH═CH—,CH₃—(CH₂)₃—CH═CH— or CH₃—CH═CH—(CH₂)₂—.

-   b) LC medium which additionally comprises one or more compounds of    the following formula:

in which the individual radicals have the following meanings:

denotes

denotes

-   -   R³ and R⁴ each, independently of one another, denote alkyl        having 1 to 12 C atoms, in which, in addition, one or two        non-adjacent CH₂ groups may be replaced by —O—, —CH═CH—, —CO—,        —O—CO— or —CO—O— in such a way that O atoms are not linked        directly to one another,    -   Z^(y) denotes —CH₂CH₂—, —CH═CH—, —CF₂O—, —OCF₂—, —CH₂O—, —OCH₂—,        —CO—O—, —O—CO—, —C₂F₄—, —CF═CF—, —CH═CH—CH₂O— or a single bond,        preferably a single bond.

The compounds of the formula ZK are preferably selected from the groupconsisting of the following sub-formulae:

in which alkyl and alkyl* each, independently of one another, denote astraight-chain alkyl radical having 1-6 C atoms, and alkenyl denotes astraight-chain alkenyl radical having 2-6 C atoms. Alkenyl preferablydenotes CH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—, CH₃—CH₂—CH═CH—,CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— or CH₃—CH═CH—(CH₂)₂—.

Especially preferred are compounds of formula ZK1.

Particularly preferred compounds of formula ZK are selected from thefollowing sub-formulae:

wherein the propyl, butyl and pentyl groups are straight-chain groups.

Most preferred are compounds of formula ZK1a.

-   c) LC medium which additionally comprises one or more compounds of    the following formula:

in which the individual radicals on each occurrence, identically ordifferently, have the following meanings:

-   -   R⁵ and R⁶ each, independently of one another, denote alkyl        having 1 to 12 C atoms, where, in addition, one or two        non-adjacent CH₂ groups may be replaced by —O—, —CH═CH—, —CO—,        —OCO— or —OCO— in such a way that O atoms are not linked        directly to one another, preferably alkyl or alkoxy having 1 to        6 C atoms,

denotes

denotes and

-   -   e denotes 1 or 2.

The compounds of the formula DK are preferably selected from the groupconsisting of the following sub-formulae:

in which alkyl and alkyl* each, independently of one another, denote astraight-chain alkyl radical having 1-6 C atoms, and alkenyl denotes astraight-chain alkenyl radical having 2-6 C atoms. Alkenyl preferablydenotes CH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—, CH₃—CH₂—CH═CH—,CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— or CH₃—CH═CH—(CH₂)₂—.

-   d) LC medium which additionally comprises one or more compounds of    the following formula:

in which the individual radicals have the following meanings:

denotes

with at least one ring F being different from cyclohexylene,

-   -   f denotes 1 or 2,    -   R¹ and R² each, independently of one another, denote alkyl        having 1 to 12 C atoms, where, in addition, one or two        non-adjacent CH₂ groups may be replaced by —O—, —CH═CH—, —CO—,        —OCO— or —OCO— in such a way that O atoms are not linked        directly to one another,    -   Z^(x) denotes —CH₂CH₂—, —CH═CH—, —CF₂O—, —OCF₂—, —CH₂O—, —OCH₂—,        —CO—O—, —O—CO—, —C₂F₄—, —CF═CF—, —CH═CH—CH₂O— or a single bond,        preferably a single bond,    -   L¹ and L² each, independently of one another, denote F, Cl,        OCF₃, CF₃, CH₃, CH₂F, CHF₂.

Preferably, both radicals L¹ and L² denote F or one of the radicals L¹and L² denotes F and the other denotes Cl.

The compounds of the formula LY are preferably selected from the groupconsisting of the following sub-formulae:

in which R¹ has the meaning indicated above, alkyl denotes astraight-chain alkyl radical having 1-6 C atoms, (O) denotes an oxygenatom or a single bond, and v denotes an integer from 1 to 6. R¹preferably denotes straight-chain alkyl having 1 to 6 C atoms orstraight-chain alkenyl having 2 to 6 C atoms, in particular CH₃, C₂H₅,n-C₃H₇, n-C₄H₉, n-C₅H₁₁, CH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—,CH₃—CH₂—CH═CH—, CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— orCH₃—CH═CH—(CH₂)₂—.

-   e) LC medium which additionally comprises one or more compounds    selected from the group consisting of the following formulae:

in which alkyl denotes C₁₋₆-alkyl, L^(x) denotes H or F, and X denotesF, Cl, OCF₃, OCHF₂ or OCH═CF₂. Particular preference is given tocompounds of the formula G1 in which X denotes F.

-   f) LC medium which additionally comprises one or more compounds    selected from the group consisting of the following formulae:

in which R⁵ has one of the meanings indicated above for R¹, alkyldenotes C₁₋₆-alkyl, d denotes 0 or 1, and z and m each, independently ofone another, denote an integer from 1 to 6. R⁵ in these compounds isparticularly preferably C₁₋₆-alkyl or -alkoxy or C₂₋₆-alkenyl, d ispreferably 1. The LC medium according to the invention preferablycomprises one or more compounds of the above-mentioned formulae inamounts of ≦5% by weight.

-   g) LC medium which additionally comprises one or more biphenyl    compounds selected from the group consisting of the following    formulae:

in which alkyl and alkyl* each, independently of one another, denote astraight-chain alkyl radical having 1-6 C atoms, and alkenyl andalkenyl* each, independently of one another, denote a straight-chainalkenyl radical having 2-6 C atoms. Alkenyl and alkenyl* preferablydenote CH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—, CH₃—CH₂—CH═CH—,CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— or CH₃—CH═CH—(CH₂)₂—.

The proportion of the biphenyls of the formulae B1 to B3 in the LCmixture is preferably at least 3% by weight, in particular 5% by weight.

The compounds of the formula B2 are particularly preferred.

The compounds of the formulae B1 to B3 are preferably selected from thegroup consisting of the following sub-formulae:

in which alkyl* denotes an alkyl radical having 1-6 C atoms. The mediumaccording to the invention particularly preferably comprises one or morecompounds of the formulae B1a and/or B2c.

-   h) LC medium which additionally comprises one or more terphenyl    compounds of the following formula:

in which R⁵ and R⁶ each, independently of one another, have one of themeanings indicated above, and

each, independently of one another, denote

in which L⁵ denotes F or Cl, preferably F, and L⁶ denotes F, Cl, OCF₃,CF₃, CH₃, CH₂F or CHF₂, preferably F.

The compounds of the formula T are preferably selected from the groupconsisting of the following sub-formulae:

in which R denotes a straight-chain alkyl or alkoxy radical having 1-7 Catoms, R* denotes a straight-chain alkenyl radical having 2-7 C atoms,(O) denotes an oxygen atom or a single bond, and m denotes an integerfrom 1 to 6. R* preferably denotes CH₂═CH—, CH₂═CHCH₂CH₂—, CH₃—CH═CH—,CH₃—CH₂—CH═CH—, CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— orCH₃—CH═CH—(CH₂)₂—.

R preferably denotes methyl, ethyl, propyl, butyl, pentyl, hexyl,methoxy, ethoxy, propoxy, butoxy or pentoxy.

The LC medium according to the invention preferably comprises theterphenyls of the formula T and the preferred sub-formulae thereof in anamount of 0.5-30% by weight, in particular 1-20% by weight.

Particular preference is given to compounds of the formulae T1, T2, T3and T21. In these compounds, R preferably denotes alkyl, furthermorealkoxy, each having 1-5 C atoms.

The terphenyls are preferably employed in mixtures according to theinvention if the An value of the mixture is to be 0.1. Preferredmixtures comprise 2-20% by weight of one or more terphenyl compounds ofthe formula T, preferably selected from the group of compounds T1 toT22.

-   i) LC medium which additionally comprises one or more quaterphenyl    compounds selected from the group consisting of the following    formulae:

wherein

-   -   R^(Q) is alkyl, alkoxy, oxyalkyl or alkoxyalkyl having 1 to 9 C        atoms or alkenyl or alkenyloxy having 2 to 9 C atoms, all of        which are optionally fluorinated,    -   X^(Q) is F, Cl, halogenated alkyl or alkoxy having 1 to 6 C        atoms or halogenated alkenyl or alkenyloxy having 2 to 6 C        atoms,    -   L^(Q1) to L^(Q6) independently of each other are H or F, with at        least one of L^(Q1) to L^(Q6) being F.

Preferred compounds of formula Q are those wherein R⁰ denotesstraight-chain alkyl with 2 to 6 C-atoms, very preferably ethyl,n-propyl or n-butyl.

Preferred compounds of formula Q are those wherein L^(Q3) and L^(Q4) areF. Further preferred compounds of formula Q are those wherein L^(Q3),L^(Q4) and one or two of L^(Q1) and L^(Q2) are F.

Preferred compounds of formula Q are those wherein X^(Q) denotes F orOCF₃, very preferably F.

The compounds of formula Q are preferably selected from the followingsubformulae

wherein R⁰ has one of the meanings of formula Q or one of its preferredmeanings given above and below, and is preferably ethyl, n-propyl orn-butyl.

Especially preferred are compounds of formula Q1, in particular thosewherein R^(Q) is n-propyl.

Preferably the proportion of compounds of formula Q in the LC medium isfrom >0 to ≦5% by weight, very preferably from 0.1 to 2% by weight, mostpreferably from 0.2 to 1.5% by weight.

Preferably the LC medium contains 1 to 5, preferably 1 or 2 compounds offormula Q.

The addition of quaterphenyl compounds of formula Q to the LC mediummixture enables to reduce ODF mura, whilst maintaining high UVabsorption, enabling quick and complete polymerization, enabling strongand quick tilt angle generation, and increasing the UV stability of theLC medium.

Besides, the addition of compounds of formula Q, which have positivedielectric anisotropy, to the LC medium with negative dielectricanisotropy allows a better control of the values of the dielectricconstants ∈_(∥) and ∈_(⊥), and in particular enables to achieve a highvalue of the dielectric constant E_(∥) while keeping the dielectricanisotropy Δ∈ constant, thereby reducing the kick-back voltage andreducing image sticking.

-   k) LC medium which additionally comprises one or more compounds    selected from the group consisting of the following formulae:

in which R¹ and R² have the meanings indicated above and preferablyeach, independently of one another, denote straight-chain alkyl having 1to 6 C atoms or straight-chain alkenyl having 2 to 6 C atoms.

Preferred media comprise one or more compounds selected from theformulae O1, O3 and O4.

-   I) LC medium which additionally comprises one or more compounds of    the following formula:

in which

denotes

-   -   R⁹ denotes H, CH₃, C₂H₅ or n-C₃H₇, (F) denotes an optional        fluorine substituent, and q denotes 1, 2 or 3, and R⁷ has one of        the meanings indicated for R¹, preferably in amounts of >3% by        weight, in particular 5% by weight and very particularly        preferably 5-30% by weight.

Particularly preferred compounds of the formula FI are selected from thegroup consisting of the following sub-formulae:

in which R⁷ preferably denotes straight-chain alkyl, and R⁹ denotes CH₃,C₂H₅ or n-C₃H₇. Particular preference is given to the compounds of theformulae FI1, FI2 and FI3.

-   m) LC medium which additionally comprises one or more compounds    selected from the group consisting of the following formulae:

in which R⁸ has the meaning indicated for R¹, and alkyl denotes astraight-chain alkyl radical having 1-6 C atoms.

-   n) LC medium which additionally comprises one or more compounds    which contain a tetrahydronaphthyl or naphthyl unit, such as, for    example, the compounds selected from the group consisting of the    following formulae:

-   -   in which    -   R¹⁰ and R¹¹ each, independently of one another, denote alkyl        having 1 to 12 C atoms, where, in addition, one or two        non-adjacent CH₂ groups may be replaced by —O—, —CH═CH—, —CO—,        —OCO— or —COO— in such a way that O atoms are not linked        directly to one another, preferably alkyl or alkoxy having 1 to        6 C atoms,    -   and R¹⁰ and R¹¹ preferably denote straight-chain alkyl or alkoxy        having 1 to 6 C atoms or straight-chain alkenyl having 2 to 6 C        atoms, and    -   Z¹ and Z² each, independently of one another, denote —C₂H₄—,        —CH═CH—, —(CH₂)₄—, —(CH₂)₃O—, —O(CH₂)₃—, —CH═CH—CH₂CH₂—,        —CH₂CH₂CH═CH—, —CH₂O—, —OCH₂—, —CO—O—, —O—CO—, —C₂F₄—, —CF═CF—,        —CF═CH—, —CH═CF—, —CH₂— or a single bond.

-   o) LC medium which additionally comprises one or more    difluorodibenzochromans and/or chromans of the following formulae:

in which

-   -   R¹¹ and R¹² each, independently of one another, have one of the        meanings indicated above for R¹¹,    -   ring M is trans-1,4-cyclohexylene or 1,4-phenylene,    -   Z^(m) —C₂H₄—, —CH₂O—, —OCH₂—, —CO—O— or —O—CO—,    -   c is 0, 1 or 2,

preferably in amounts of 3 to 20% by weight, in particular in amounts of3 to 15% by weight.

Particularly preferred compounds of the formulae BC, CR and RC areselected from the group consisting of the following sub-formulae:

in which alkyl and alkyl* each, independently of one another, denote astraight-chain alkyl radical having 1-6 C atoms, (O) denotes an oxygenatom or a single bond, c is 1 or 2, and alkenyl and alkenyl* each,independently of one another, denote a straight-chain alkenyl radicalhaving 2-6 C atoms. Alkenyl and alkenyl* preferably denote CH₂═CH—,CH₂═CHCH₂CH₂—, CH₃—CH═CH—, CH₃—CH₂—CH═CH—, CH₃—(CH₂)₂—CH═CH—,CH₃—(CH₂)₃—CH═CH— or CH₃—CH═CH—(CH₂)₂—.

Very particular preference is given to mixtures comprising one, two orthree compounds of the formula BC-2.

-   p) LC medium which additionally comprises one or more fluorinated    phenanthrenes and/or dibenzofurans of the following formulae:

in which R¹¹ and R¹² each, independently of one another, have one of themeanings indicated above for R¹¹, b denotes 0 or 1, L denotes F, and rdenotes 1, 2 or 3.

Particularly preferred compounds of the formulae PH and BF are selectedfrom the group consisting of the following sub-formulae:

in which R and R′ each, independently of one another, denote astraight-chain alkyl or alkoxy radical having 1-7 C atoms.

-   q) LC medium which additionally comprises one or more monocyclic    compounds of the following formula

wherein

-   -   R¹ and R² each, independently of one another, denote alkyl        having 1 to 12 C atoms, where, in addition, one or two        non-adjacent CH₂ groups may be replaced by —O—, —CH═CH—, —CO—,        —OCO— or —COO— in such a way that O atoms are not linked        directly to one another, preferably alkyl or alkoxy having 1 to        6 C atoms,    -   L¹ and L² each, independently of one another, denote F, Cl,        OCF₃, CF₃, CH₃, CH₂F, CHF₂.

Preferably, both L¹ and L² denote F or one of L¹ and L² denotes F andthe other denotes Cl,

The compounds of the formula Y are preferably selected from the groupconsisting of the following sub-formulae:

in which, Alkyl and Alkyl* each, independently of one another, denote astraight-chain alkyl radical having 1-6 C atoms, Alkoxy denotes astraight-chain alkoxy radical having 1-6 C atoms, Alkenyl and Alkenyl*each, independently of one another, denote a straight-chain alkenylradical having 2-6 C atoms, and O denotes an oxygen atom or a singlebond. Alkenyl and Alkenyl* preferably denote CH₂═CH—, CH₂═CHCH₂CH₂—,CH₃—CH═CH—, CH₃—CH₂—CH═CH—, CH₃—(CH₂)₂—CH═CH—, CH₃—(CH₂)₃—CH═CH— orCH₃—CH═CH—(CH₂)₂—.

Particularly preferred compounds of the formula Y are selected from thegroup consisting of the following sub-formulae:

wherein Alkoxy preferably denotes straight-chain alkoxy with 3, 4, or 5C atoms.

-   r) LC medium which, apart from the polymerizable compounds according    to the invention, in particular of the formula I or sub-formulae    thereof and the comonomers, comprises no compounds which contain a    terminal vinyloxy group (—O—CH═CH₂).-   s) LC medium which comprises 1 to 5, preferably 1, 2 or 3,    polymerizable compounds, preferably selected from polymerizable    compounds according to the invention, in particular of the formula I    or sub-formulae thereof.-   t) LC medium in which the proportion of polymerizable compounds, in    particular of the formula I or sub-formulae thereof, in the mixture    as a whole is 0.05 to 5%, preferably 0.1 to 1%.-   u) LC medium which comprises 1 to 8, preferably 1 to 5, compounds of    the formulae CY1, CY2, PY1 and/or PY2. The proportion of these    compounds in the mixture as a whole is preferably 5 to 60%,    particularly preferably 10 to 35%. The content of these individual    compounds is preferably in each case 2 to 20%.-   v) LC medium which comprises 1 to 8, preferably 1 to 5, compounds of    the formulae CY9, CY10, PY9 and/or PY10. The proportion of these    compounds in the mixture as a whole is preferably 5 to 60%,    particularly preferably 10 to 35%. The content of these individual    compounds is preferably in each case 2 to 20%.-   w) LC medium which comprises 1 to 10, preferably 1 to 8, compounds    of the formula ZK, in particular compounds of the formulae ZK1, ZK2    and/or ZK6. The proportion of these compounds in the mixture as a    whole is preferably 3 to 25%, particularly preferably 5 to 45%. The    content of these individual compounds is preferably in each case 2    to 20%.-   x) LC medium in which the proportion of compounds of the formulae    CY, PY and ZK in the mixture as a whole is greater than 70%,    preferably greater than 80%.-   y) LC medium in which the LC host mixture contains one or more    compounds containing an alkenyl group, preferably selected from the    group consisting of formula CY, PY and LY, wherein one or both of R¹    and R² denote straight-chain alkenyl having 2-6 C atoms, formula ZK    and DK, wherein one or both of R³ and R⁴ or one or both of R⁵ and R⁶    denote straight-chain alkenyl having 2-6 C atoms, and formula B2 and    B3, very preferably selected from formulae CY15, CY16, CY24, CY32,    PY15, PY16, ZK3, ZK4, DK3, DK6, B2 and B3, most preferably selected    from formulae ZK3, ZK4, B2 and B3. The concentration of these    compounds in the LC host mixture is preferably from 2 to 70%, very    preferably from 3 to 55%.-   z) LC medium which contains one or more, preferably 1 to 5,    compounds selected of formula PY1-PY8, very preferably of formula    PY2. The proportion of these compounds in the mixture as a whole is    preferably 1 to 30%, particularly preferably 2 to 20%. The content    of these individual compounds is preferably in each case 1 to 20%.-   z1) LC medium which contains one or more, preferably 1, 2 or 3,    compounds of formula T2. The content of these compounds in the    mixture as a whole is preferably 1 to 20%.-   z2) LC medium in which the LC host mixture contains one or more,    preferably 1, 2 or 3, compounds of formula BF1, and one or more,    preferably 1, 2 or 3, compounds selected from formulae AY14, AY15    and AY16, very preferably of formula AY14. The proportion of the    compounds of formula AY14-AY16 in the LC host mixture is preferably    from 2 to 35%, very preferably from 3 to 30%. The proportion of the    compounds of formula BF1 in the LC host mixture is preferably from    0.5 to 20%, very preferably from 1 to 15%. Further preferably the LC    host mixture according to this preferred embodiment contains one or    more, preferably 1, 2 or 3 compounds of formula T, preferably    selected from formula T1, T2 and T5, very preferably from formula T2    or T5. The proportion of the compounds of formula T in the LC host    mixture medium is preferably from 0.5 to 15%, very preferably from 1    to 10%.

In a second preferred embodiment the LC medium contains an LC hostmixture based on compounds with positive dielectric anisotropy. Such LCmedia are especially suitable for use in PS-OCB-, PS-TN-, PS-Posi-VA-,PS-IPS- or PS-FFS-displays.

Particularly preferred is an LC medium of this second preferredembodiment, which contains one or more compounds selected from the groupconsisting of compounds of formula AA and BB

and optionally contains, in addition to the compounds of formula AAand/or BB, one or more compounds of formula CC

in which the individual radicals have the following meanings:

each, independently of one another, and on each occurrence, identicallyor differently

each, independently of one another, and on each occurrence, identicallyor differently

-   R²¹, R³¹, R⁴¹, R⁴² each, independently of one another, alkyl,    alkoxy, oxaalkyl or alkoxyalkyl having 1 to 9 C atoms or alkenyl or    alkenyloxy having 2 to 9 C atoms, all of which are optionally    fluorinated,-   X⁰ F, Cl, halogenated alkyl or alkoxy having 1 to 6 C atoms or    halogenated alkenyl or alkenyloxy having 2 to 6 C atoms,-   Z³¹ —CH₂CH₂—, —CF₂CF₂—, —COO—, trans-CH═CH—, trans-CF═CF—, —CH₂O— or    a single bond, preferably —CH₂CH₂—, —COO—, trans-CH═CH— or a single    bond, particularly-   Z⁴¹, Z⁴² —CH₂CH₂—, —COO—, trans-CH═CH—, trans-CF═CF—, —CH₂O—,    —CF₂O—, —C≡C— or a single bond, preferably a single bond,-   L²¹, L²², L³¹, L³² H or F,-   g 0, 1, 2 or 3,-   h 0, 1, 2 or 3.-   X⁰ is preferably F, Cl, CF₃, CHF₂, OCF₃, OCHF₂, OCFHCF₃, OCFHCHF₂,    OCFHCHF₂, OCF₂CH₃, OCF₂CHF₂, OCF₂CHF₂, OCF₂CF₂CHF₂, OCF₂CF₂CHF₂,    OCFHCF₂CF₃, OCFHCF₂CHF₂, OCF₂CF₂CF₃, OCF₂CF₂CClF₂, OCClFCF₂CF₃ or    CH═CF₂, very preferably F or OCF₃

The compounds of formula AA are preferably selected from the groupconsisting of the following formulae:

in which A²¹, R²¹, X⁰, L²¹ and L²² have the meanings given in formulaAA, L²³ and L²⁴ each, independently of one another, are H or F, and X⁰is preferably F. Particularly preferred are compounds of formulae AA1and AA2.

Particularly preferred compounds of formula AA1 are selected from thegroup consisting of the following subformulae:

in which R²¹, X⁰, L²¹ and L²² have the meaning given in formula AA1,L²³, L²⁴, L²⁵ and L²⁶ are each, independently of one another, H or F,and X⁰ is preferably F.

Very particularly preferred compounds of formula AA1 are selected fromthe group consisting of the following subformulae:

In which R²¹ is as defined in formula AA1.

Very preferred compounds of formula AA2 are selected from the groupconsisting of the following subformulae:

in which R²¹, X⁰, L²¹ and L²² have the meaning given in formula AA2,L²³, L²⁴, L²⁵ and L²⁶ each, independently of one another, are H or F,and X⁰ is preferably F.

Very particularly preferred compounds of formula AA2 are selected fromthe group consisting of the following subformulae:

in which R²¹ and X⁰ are as defined in formula AA2.

Particularly preferred compounds of formula AA3 are selected from thegroup consisting of the following subformulae:

in which R²¹, X⁰, L²¹ and L²² have the meaning given in formula AA3, andX⁰ is preferably F.

Particularly preferred compounds of formula AA4 are selected from thegroup consisting of the following subformulae:

in which R²¹ is as defined in formula AA4.

The compounds of formula BB are preferably selected from the groupconsisting of the following formulae:

in which g, A³¹, A³², R³¹, X⁰, L³¹ and L³² have the meanings given informula BB, and X⁰ is preferably F. Particularly preferred are compoundsof formulae BB1 and BB2.

Particularly preferred compounds of formula BB1 are selected from thegroup consisting of the following subformulae:

in which R³¹, X⁰, L³¹ and L³² have the meaning given in formula BB1, andX⁰ is preferably F.

Very particularly preferred compounds of formula BB1a are selected fromthe group consisting of the following subformulae:

in which R³¹ is as defined in formula BB1.

Very particularly preferred compounds of formula BB1 b are selected fromthe group consisting of the following subformulae:

in which R³¹ is as defined in formula BB1.

Particularly preferred compounds of formula BB2 are selected from thegroup consisting of the following subformulae:

in which R³¹, X⁰, L³¹ and L³² have the meaning given in formula BB2,L³³, L³⁴, L³⁵ and L³⁶ are each, independently of one another, H or F,and X⁰ is preferably F.

Very particularly preferred compounds of formula BB2 are selected fromthe group consisting of the following subformulae:

in which R³¹ is as defined in formula BB2.

Very particularly preferred compounds of formula BB2b are selected fromthe group consisting of the following subformulae

in which R³¹ is as defined in formula BB2.

Very particularly preferred compounds of formula BB2c are selected fromthe group consisting of the following subformulae:

in which R³¹ is as defined in formula BB2.

Very particularly preferred compounds of formula BB2d and BB2e areselected from the group consisting of the following subformulae:

in which R³¹ is as defined in formula BB2.

Very particularly preferred compounds of formula BB2f are selected fromthe group consisting of the following subformulae:

in which R³¹ is as defined in formula BB2.

Very particularly preferred compounds of formula BB2g are selected fromthe group consisting of the following subformulae:

in which R³¹ is as defined in formula BB2.

Very particularly preferred compounds of formula BB2h are selected fromthe group consisting of the following subformulae:

in which R³¹ and X⁰ are as defined in formula BB2.

Very particularly preferred compounds of formula BB2i are selected fromthe group consisting of the following subformulae:

in which R³¹ and X⁰ are as defined in formula BB2.

Very particularly preferred compounds of formula BB2k are selected fromthe group consisting of the following subformulae:

in which R³¹ and X⁰ are as defined in formula BB2.

Alternatively to, or in addition to, the compounds of formula BB1 and/orBB2 the LC media may also comprise one or more compounds of formula BB3as defined above.

Particularly preferred compounds of formula BB3 are selected from thegroup consisting of the following subformulae:

in which R³¹ is as defined in formula BB3.

Preferably the LC media according to this second preferred embodimentcomprise, in addition to the compounds of formula AA and/or BB, one ormore dielectrically neutral compounds having a dielectric anisotropy inthe range from −1.5 to +3, preferably selected from the group ofcompounds of formula CC as defined above.

Particularly preferred compounds of formula CC are selected from thegroup consisting of the following subformulae:

In which R⁴¹ and R⁴² have the meanings given in formula CC, andpreferably denote each, independently of one another, alkyl, alkoxy,fluorinated alkyl or fluorinated alkoxy with 1 to 7 C atoms, or alkenyl,alkenyloxy, alkoxyalkyl or fluorinated alkenyl with 2 to 7 C atoms, andL⁴ is H or F.

Preferably the LC media according to this second preferred embodimentcomprise, in addition or alternatively to the dielectrically neutralcompounds of formula CC, one or more dielectrically neutral compoundshaving a dielectric anisotropy in the range from −1.5 to +3, selectedfrom the group of compounds of formula DD.

In which A⁴¹, A⁴², Z⁴¹, Z⁴², R⁴¹, R⁴² and h have the meanings given informula CC.

Particularly preferred compounds of formula DD are selected from thegroup consisting of the following subformulae:

in which R⁴¹ and R⁴² have the meanings given in formula DD and R⁴¹preferably denotes alkyl bedeutet, and in formula DD1 R⁴² preferablydenotes alkenyl, particularly preferably —(CH₂)₂—CH═CH—CH₃, and informula DD2 R⁴² preferably denotes alkyl, —(CH₂)₂—CH═CH₂ or—(CH₂)₂—CH═CH—CH₃.

The compounds of formula AA and BB are preferably used in the LC mediumaccording to the invention in a concentration from 2% to 60%, morepreferably from 3% to 35%, and very particularly preferably from 4% to30% in the mixture as a whole.

The compounds of formula CC and DD are preferably used in the LC mediumaccording to the invention in a concentration from 2% to 70%, morepreferably from 5% to 65%, even more preferably from 10% to 60%, andvery particularly preferably from 10%, preferably 15%, to 55% in themixture as a whole.

The combination of compounds of the preferred embodiments mentionedabove with the polymerized compounds described above causes lowthreshold voltages, low rotational viscosities and very goodlow-temperature stabilities in the LC media according to the inventionat the same time as constantly high clearing points and high HR values,and allows the rapid establishment of a particularly low pretilt anglein PSA displays. In particular, the LC media exhibit significantlyshortened response times, in particular also the grey-shade responsetimes, in PSA displays compared with the media from the prior art.

The LC media and LC host mixtures of the present invention preferablyhave a nematic phase range of at least 80 K, particularly preferably atleast 100 K, and a rotational viscosity ≦250 mPa·s, preferably ≦200mPa·s, at 20° C.

In the VA-type displays according to the invention, the molecules in thelayer of the LC medium in the switched-off state are alignedperpendicular to the electrode surfaces (homeotropically) or have atilted homeotropic alignment. On application of an electrical voltage tothe electrodes, a realignment of the LC molecules takes place with thelongitudinal molecular axes parallel to the electrode surfaces.

LC media according to the invention based on compounds with negativedielectric anisotropy according to the first preferred embodiment, inparticular for use in displays of the PS-VA and PS-UB-FFS type, have anegative dielectric anisotropy Δ∈, preferably from −0.5 to −10, inparticular from −2.5 to −7.5, at 20° C. and 1 kHz.

The birefringence Δn in LC media according to the invention for use indisplays of the PS-VA and PS-UB-FFS type is preferably below 0.16,particularly preferably from 0.06 to 0.14, very particularly preferablyfrom 0.07 to 0.12.

In the OCB-type displays according to the invention, the molecules inthe layer of the LC medium have a “bend” alignment. On application of anelectrical voltage, a realignment of the LC molecules takes place withthe longitudinal molecular axes perpendicular to the electrode surfaces.

LC media according to the invention for use in displays of the PS-OCB,PS-TN, PS-IPS, PS-posi-VA and PS-FFS type are preferably those based oncompounds with positive dielectric anisotropy according to the secondpreferred embodiment, and preferably have a positive dielectricanisotropy Δ∈ from +4 to +17 at 20° C. and 1 kHz.

The birefringence Δn in LC media according to the invention for use indisplays of the PS-OCB type is preferably from 0.14 to 0.22,particularly preferably from 0.16 to 0.22.

The birefringence Δn in LC media according to the invention for use indisplays of the PS-TN—, PS-posi-VA-, PS-IPS- order PS-FFS-type ispreferably from 0.07 to 0.15, particularly preferably from 0.08 to 0.13.

LC media according to the invention, based on compounds with positivedielectric anisotropy according to the second preferred embodiment, foruse in displays of the PS-TN—, PS-posi-VA-, PS-IPS- order PS-FFS-type,preferably have a positive dielectric anisotropy Δ∈ from +2 to +30,particularly preferably from +3 to +20, at 20° C. and 1 kHz.

The LC media according to the invention may also comprise furtheradditives which are known to the person skilled in the art and aredescribed in the literature, such as, for example, polymerizationinitiators, inhibitors, stabilisers, surface-active substances or chiraldopants. These may be polymerizable or non-polymerizable. Polymerizableadditives are accordingly ascribed to the polymerizable component orcomponent A). Non-polymerizable additives are accordingly ascribed tothe non-polymerizable component or component B).

In a preferred embodiment the LC media contain one or more chiraldopants, preferably in a concentration from 0.01 to 1%, very preferablyfrom 0.05 to 0.5%. The chiral dopants are preferably selected from thegroup consisting of compounds from Table B below, very preferably fromthe group consisting of R- or S-1011, R- or S-2011, R- or S-3011, R- orS-4011, and R- or S-5011.

In another preferred embodiment the LC media contain a racemate of oneor more chiral dopants, which are preferably selected from the chiraldopants mentioned in the previous paragraph.

Furthermore, it is possible to add to the LC media, for example, 0 to15% by weight of pleochroic dyes, furthermore nanoparticles, conductivesalts, preferably ethyldimethyldodecylammonium 4-hexoxybenzoate,tetrabutylammonium tetraphenylborate or complex salts of crown ethers(cf., for example, Haller et al., Mol. Cryst. Liq. Cryst. 24, 249-258(1973)), for improving the conductivity, or substances for modifying thedielectric anisotropy, the viscosity and/or the alignment of the nematicphases. Substances of this type are described, for example, in DE-A 2209 127, 22 40 864, 23 21 632, 23 38 281, 24 50 088, 26 37 430 and 28 53728.

The individual components of the preferred embodiments a)-z) of the LCmedia according to the invention are either known or methods for thepreparation thereof can readily be derived from the prior art by theperson skilled in the relevant art, since they are based on standardmethods described in the literature. Corresponding compounds of theformula CY are described, for example, in EP-A-0 364 538. Correspondingcompounds of the formula ZK are described, for example, in DE-A-26 36684 and DE-A-33 21 373.

The LC media which can be used in accordance with the invention areprepared in a manner conventional per se, for example by mixing one ormore of the above-mentioned compounds with one or more polymerizablecompounds as defined above, and optionally with furtherliquid-crystalline compounds and/or additives. In general, the desiredamount of the components used in lesser amount is dissolved in thecomponents making up the principal constituent, advantageously atelevated temperature. It is also possible to mix solutions of thecomponents in an organic solvent, for example in acetone, chloroform ormethanol, and to remove the solvent again, for example by distillation,after thorough mixing. The invention furthermore relates to the processfor the preparation of the LC media according to the invention.

It goes without saying to the person skilled in the art that the LCmedia according to the invention may also comprise compounds in which,for example, H, N, O, Cl, F have been replaced by the correspondingisotopes like deuterium etc.

The following examples explain the present invention without restrictingit.

However, they show the person skilled in the art preferred mixtureconcepts with compounds preferably to be employed and the respectiveconcentrations thereof and combinations thereof with one another. Inaddition, the examples illustrate which properties and propertycombinations are accessible.

The following abbreviations are used:

(n, m, z: in each case, independently of one another, 1, 2, 3, 4, 5 or6)

TABLE A

In a preferred embodiment of the present invention, the LC mediaaccording to the invention comprise one or more compounds selected fromthe group consisting of compounds from Table A.

TABLE B Table B shows possible chiral dopants which can be added to theLC media according to the invention.

C 15

CB 15

CM 21

R/S-811

CM 44

CM 45

CM 47

CN

R/S-2011

R/S-3011

R/S-4011

R/S-5011

R/S-1011

The LC media preferably comprise 0 to 10% by weight, in particular 0.01to 5% by weight, particularly preferably 0.1 to 3% by weight, ofdopants. The LC media preferably comprise one or more dopants selectedfrom the group consisting of compounds from Table B.

TABLE C Table C shows possible stabilisers which can be added to the LCmedia according to the invention.

(n here denotes an integer from 1 to 12, preferable 1, 2, 3, 4, 5, 6, 7or 8, terminal methyl groups are not shown).

The LC media preferably comprise 0 to 10% by weight, in particular 1 ppmto 5% by weight, particularly preferably 1 ppm to 1% by weight, ofstabilisers. The LC media preferably comprise one or more stabilisersselected from the group consisting of compounds from Table C.

TABLE D Table D shows illustrative compounds which can be used in the LCmedia in accordance with the present invention, preferable as reactivemesogenic compounds.

RM-1

RM-2

RM-3

RM-4

RM-5

RM-6

RM-7

RM-8

RM-9

RM-10

RM-11

RM-12

RM-13

RM-14

RM-15

RM-16

RM-17

RM-18

RM-19

RM-20

RM-21

RM-22

RM-23

RM-24

RM-25

RM-26

RM-27

RM-28

RM-29

RM-30

RM-31

RM-32

RM-33

RM-34

RM-35

RM-36

RM-37

RM-38

RM-39

RM-40

RM-41

RM-42

RM-43

RM-44

RM-45

RM-46

RM-47

RM-48

RM-49

RM-50

RM-51

RM-52

RM-53

RM-54

RM-55

RM-56

RM-57

RM-58

RM-59

RM-60

RM-61

RM-62

RM-63

RM-64

RM-65

RM-66

RM-67

RM-68

RM-69

RM-70

RM-71

In a preferred embodiment of the present invention, the mesogenic mediacomprise one or more compounds selected from the group of the compoundsfrom Table D.

In addition, the following abbreviations and symbols are used:

-   V₀ threshold voltage, capacitive [V] at 20° C.,-   n_(e) extraordinary refractive index at 20° C. and 589 nm,-   n_(o) ordinary refractive index at 20° C. and 589 nm,-   Δn optical anisotropy at 20° C. and 589 nm,-   ∈_(⊥) dielectric permittivity perpendicular to the director at    20° C. and 1 kHz,-   ∈∥ dielectric permittivity parallel to the director at 20° C. and 1    kHz,-   Δ∈ dielectric anisotropy at 20° C. and 1 kHz,-   cl.p., T(N,I) clearing point [° C.],-   γ₁ rotational viscosity at 20° C. [mPa·s],-   K₁ elastic constant, “splay” deformation at 20° C. [pN],-   K₂ elastic constant, “twist” deformation at 20° C. [pN],-   K₃ elastic constant, “bend” deformation at 20° C. [pN].

Unless explicitly noted otherwise, all concentrations in the presentapplication are quoted in percent by weight and relate to thecorresponding mixture as a whole, comprising all solid orliquid-crystalline components, without solvents.

Unless explicitly noted otherwise, all temperature values indicated inthe present application, such as, for example, for the melting pointT(C,N), the transition from the smectic (S) to the nematic (N) phaseT(S,N) and the clearing point T(N,I), are quoted in degrees Celsius (°C.). M.p. denotes melting point, cl.p.=clearing point. Furthermore,C=crystalline state, N=nematic phase, S=smectic phase and I=isotropicphase. The data between these symbols represent the transitiontemperatures.

All physical properties are and have been determined in accordance with“Merck Liquid Crystals, Physical Properties of Liquid Crystals”, StatusNov. 1997, Merck KGaA, Germany, and apply for a temperature of 20° C.,and Δn is determined at 589 nm and Δ∈ at 1 kHz, unless explicitlyindicated otherwise in each case.

The term “threshold voltage” for the present invention relates to thecapacitive threshold (V₀), also known as the Freedericks threshold,unless explicitly indicated otherwise. In the examples, the opticalthreshold may also, as generally usual, be quoted for 10% relativecontrast (V₁₀).

Unless stated otherwise, the process of polymerising the polymerizablecompounds in the PSA displays as described above and below is carriedout at a temperature where the LC medium exhibits a liquid crystalphase, preferably a nematic phase, and most preferably is carried out atroom temperature.

Unless stated otherwise, methods of preparing test cells and measuringtheir electrooptical and other properties are carried out by the methodsas described hereinafter or in analogy thereto.

The display used for measurement of the capacitive threshold voltageconsists of two plane-parallel glass outer plates at a separation of 25μm, each of which has on the inside an electrode layer and an unrubbedpolyimide alignment layer on top, which effect a homeotropic edgealignment of the liquid-crystal molecules.

The display or test cell used for measurement of the tilt anglesconsists of two plane-parallel glass outer plates at a separation of 4μm, each of which has on the inside an electrode layer and a polyimidealignment layer on top, where the two polyimide layers are rubbedantiparallel to one another and effect a homeotropic edge alignment ofthe liquid-crystal molecules.

The polymerizable compounds are polymerized in the display or test cellby irradiation with UVA light of defined intensity for a prespecifiedtime, with a voltage simultaneously being applied to the display(usually 10 V to 30 V alternating current, 1 kHz). In the examples,unless indicated otherwise, a metal halide lamp and an intensity of 100mW/cm² is used for polymerization. The intensity is measured using astandard UVA meter (Hoenle UV-meter high end with UVA sensor).

The tilt angle is determined by crystal rotation experiment(Autronic-Melchers TBA-105). A low value (i.e. a large deviation fromthe 90° angle) corresponds to a large tilt here.

The VHR value is measured as follows: 0.3% of a polymerizable monomericcompound is added to the LC host mixture, and the resultant mixture isintroduced into VA-VHR test cells which comprise an unrubbedVA-polyimide alignment layer. The LC-layer thickness d is approx. 6 μm,unless stated othewise. The VHR value is determined after 5 min at 100°C. before and after UV exposure at 1 V, 60 Hz, 64 μs pulse (measuringinstrument: Autronic-Melchers VHRM-105).

Without further elaboration, it is believed that one skilled in the artcan, using the preceding description, utilize the present invention toits fullest extent. The preceding preferred specific embodiments are,therefore, to be construed as merely illustrative, and not limitative ofthe remainder of the disclosure in any way whatsoever.

The entire disclosures of all applications, patents and publications,cited herein and of corresponding application No. EP 14002944.8, filedAug. 25, 2014, are incorporated by reference herein.

Example 1

Reactive mesogen 1 is prepared as follows.

1a: To a solution of sodium metaborate tetrahydrate (15.0 g, 53.8 mmol)in dist. water (140 ml) is added the solution of 4-(benzyloxy)phenylboronic acid (16.00 g, 70.0 mmol) and 3-bromoiodobenzene (25.00 g, 88.0mmol) in 140 ml THF. After thoroughly degassing with argon,bis(triphenylphosphine)palladium(II) chloride (1.90 g, 2.6 mmol) isadded, followed by the addition of hydrazinium hydroxide (0.066 ml, 1.4mmol). The reaction mixture is heated to reflux and stirred for 5 hours.After cooling to room temperature, the reaction mixture is carefullyneutralized with 2 M HCl acid. The aqueous phase is separated andextracted with ethyl acetate. The organic phase is combined and driedover anhydrous sodium sulfate. After removing organic solvent, the oilyresidue is purified by column chromatography on silica gel with tolueneas eluent to afford 1a (26.8 g).

1b: To a solution of 1a (10.00 g, 26.0 mmol) and bis(pinacolato)diboron(12.00 g, 46.3 mmol) in 200 ml 1,4-dioxane was added sodium acetate(6.00 g, 61.1 mmol). After thoroughly degassing with argon,bis(triphenylphosphine)-palladium(II) chloride (1.3 g, 1.78 mmol) isadded. The reaction mixture is heated to reflux and stirred for 4 hours.After cooling to room temperature, 200 ml dist. water is added. Theaqueous phase is separated and extracted with methyl t-butyl ether. Theorganic phase is combined and dried over anhydrous sodium sulfate, andfiltrated through silica gel. After removing solvent in vacuo, the oilyresidue is purified by column chromatography on silica gel with tolueneas eluent. The obtained crude product is further recrystallized fromethanol to afford 1b (4.7 g).

1c: To a solution of sodium metaborate tetrahydrate (2.60 g, 9.34 mmol)in dist. water (50 ml) is added the solution of 1b (4.70 g, 12.0 mmol)in 50 ml THF. After thoroughly degassing with argon,bis(triphenylphosphine)palladium(II) chloride (0.35 g, 0.49 mmol) isadded, followed by the addition of hydrazinium hydroxide (0.011 ml, 0.24mmol). The reaction mixture is heated to reflux and stirred overnight.After cooling to room temperature, the reaction mixture is carefullyneutralized with 2 M HCl acid. The precipitated crude product isrecrystallized from toluene/ethyl acetate solvent mixture to afford 1c(1.5 g).

1d: A solution of 1c (1.5 g, 3.82 mmol) in tetrahydrofuran (10 ml) istreated with palladium (5%) on activated charcoal (0.5 g) and submittedto hydrogenation for 20 hs. The catalyst is then filtered off, and theremaining solution is concentrated in vacuo. The residue isrecrystallized from toluene/ethyl acetate solvent mixture to provide 1d(0.8 g).

1: 4-(dimethylamino)pyridine (0.033 g, 0.27 mmol) and pyridine (1.0 ml,12.0 mmol) are added to a suspension of 1d (0.8 g, 2.7 mmol) indichloromethane (60 ml), to which the solution of methacrylic acidanhydride (1.0 ml, 6.0 mmol) in 10 ml dichloromethane is added dropwiseat 5° C. The reaction mixture is stirred for 20 h at room temperature.After removing solvent in vacuo, the oily residue is purified by silicagel chromatography with dichloromethane as eluent. The obtained productis recrystallized from ethanol/diethylether solvent mixture to affordwhite crystals of 1 (0.4 g, mp. 72° C.).

Example 2

Reactive mesogen 2 is prepared as follows.

2a: To a solution of 4-bromo-2-fluorophenol (25.30 g, 128.0 mmol) andbis(pinacolato)diboron (29.00 g, 114.0 mmol) in 300 ml 1,4-dioxane wasadded potassium acetate (38.00 g, 387.0 mmol). After thoroughlydegassing with argon, bis(triphenylphosphine)-palladium(II) chloride(2.8 g, 3.80 mmol) is added. The reaction mixture is heated to refluxand stirred for 4 hours. After cooling to room temperature, 800 ml dist.water is added. The aqueous phase is separated and extracted with methylt-butyl ether. The organic phase is combined and dried over anhydroussodium sulfate, and filtrated through silica gel. After removing solventin vacuo, the oily residue is purified by column chromatography onsilica gel with heptane/methyl t-butyl ether 3:2 as eluent. The obtainedcrude product is further recrystallized from heptane to afford 2a aswhite crystals (19.9 g).

2b: To a solution of 2a (19.9 g, 83.6 mmol) and 1-bormo-3-iodobenzene(23.48 g, 83.0 mmol) in 200 ml toluene was added 100 ml dist. water and50 ml ethanol. Sodium carbonate (21.99 g, 207.5 mmol) is added. Theresulted suspension is degassed carefully with argon.Tetrakis(triphenylphosphine)palladium(O) (3.44 g, 2.98 mmol) is thenadded. The reaction mixture is heated to reflux and stirred overnight.After cooling to room temperature, the reaction mixture is neutralizedcarefully with 6 M HCl acid under cooling to pH˜7. The aqueous phase isextracted with ethylacetate. The organic phase is combined and washedwith sat. aq. NaCl solution, dried over sodium sulfate. After removingsolvent in vacuo, the solid residue is purified by column chromatographywith ethyl acetate/toluene 1:9 as eluent. The crude product is furtherrecrystallized from heptane/ethyl acetate solvent mixture to provide 2bas solid (7.8 g).

2c: To a solution of 2b (7.7 g, 28.8 mmol) in 70 ml ethyl methylketone(EMK) is added potassium carbonate (4.58 g. 33.0 mmol) in severalportions. The reaction mixture is heated to 60° C., to which thesolution of 3-bromo-1-propanol (4.4 g, 31.7 mmol) in 10 ml EMK is addeddropwise. The reaction mixture is stirred 3 hours while refluxing. Aftercooling to room temperature, the reaction mixture is filtrated. Thesolid residue is washed thoroughly with aceton. After removing solventin vacuo, the oily residue is purified by silica gel chromatography withheptane/toluene 7:3 as eluent. The crude product is furtherrecrystallized from heptane/ethyl acetate 4:1 to provide 2c as whitesolid (7.7 g).

2d: To a solution of sodium metaborate tetrahydrate (5.94 g, 42.6 mmol)in dist. water (20 ml) is added the solution of 2c (7.7 g, 23.6 mmol)and 4-hydroxyphenylboronic acid pinacol ester (5.72 g, 26.0 mmol) in 70ml THF. After thoroughly degassing with argon,bis(triphenylphosphine)-palladium(II) chloride (0.95 g, 1.3 mmol) isadded, followed by the addition of hydrazinium hydroxide (0.05 ml, 1.0mmol). The reaction mixture is heated to reflux and stirred for 5 hours.After cooling to room temperature, the reaction mixture is carefullyneutralized with 2 M HCl acid. The aqueous phase is separated andextracted with ethyl acetate. The organic phase is combined and driedover anhydrous sodium sulfate. After removing organic solvent, the oilyresidue is purified by column chromatography on silica gel withtoluene/ethyl acetate 3:2 as eluent to afford 2d as yellowish solid (6.1g).

2: Methacrylic acid (3.98 g, 46.3 mmol) and 4-(dimethylamino)pyridine(0.20 g, 1.6 mmol) is added to a suspension of 2d (6.10 g, 17.8 mmol) indichloromethane (70 ml). The reaction mixture is treated dropwise at 0°C. with a solution of N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide(7.47 g, 48.1 mmol) in dichloromethane (70 ml) and stirred for 20 hs atroom temperature. The reaction mixture is concentrated in vacuo, and theoily residue is purified by column chromatography on silica gel withheptane/ethyl acetate 7:3 as eluent. The obtained product isrecrystallized from heptane/ethanol 1:1 to afford white crystals of 2(4.0 g, mp. 75° C.).

Example 3

Reactive mesogen 3 is prepared as follows.

3a is prepared with the exactly same method as described in 1a.

3b: To a solution of 3a (14.9 g, 42.2 mmol) and 4-hydroxy phenyl boronicacid (6.73 g, 46.4 mmol) in 140 ml 1,4-dioxane was added 35 ml dist.water. Sodium carbonate (8.94 g, 84.3 mmol) is added. The resultedsuspension is degassed carefully with argon.Bis(triphenylphosphine)-palladium(II) chloride (0.93 g, 1.26 mmol) isthen added. The reaction mixture is heated to reflux and stirredovernight. After cooling to room temperature, the reaction mixture isneutralized carefully with 6 M HCl acid under cooling to pH˜7. Theaqueous phase is extracted with ethylacetate. The organic phase iscombined and washed with sat. aq. NaCl solution, dried over sodiumsulfate. After removing solvent in vacuo, the solid residue is purifiedby column chromatography with ethyl acetate/toluene 1:9 as eluent. Thecrude product is further recrystallized from ethanol to provide 3b asbrown solid (7.1 g).

3c: To a solution of 3b (7.00 g, 19.6 mmol) in 180 ml dichloromethaneare added 4-(dimethylamino)pyridine (0.24 g, 1.96 mmol) andN-(3-dimethylaminopropyl)-N′-ethylcarbodiimidhydrochlorid (DAPECl) (5.24g, 27.3 mmol). The reaction mixture is stirred at room temperatureovernight. 200 ml water is added. The aqueous phase is extracted withdichloromethane. The organic phase is combined and dried over anhydroussodium sulfate. After removing solvent in vacuo, the solid residue ispurified by column chromatography with dichloromethane as eluent toprovide 3c as off-white solid (9.06 g).

3d: A solution of 3c (9.0 g, 17.8 mmol) in tetrahydrofuran (90 ml) istreated with palladium (5%) on activated charcoal (1.5 g) and submittedto hydrogenation for 20 hs. The catalyst is then filtered off, and theremaining solution is concentrated in vacuo. The residue isrecrystallized from toluene/heptane solvent mixture to provide 3d aswhite solid (3.8 g).

3: Methacrylic acid (2.95 ml, 34.8 mmol) and 4-(dimethylamino)pyridine(0.14 g, 1.16 mmol) is added to a suspension of 3d (3.80 g, 11.6 mmol)in dichloromethane (40 ml). The reaction mixture is treated dropwise at0° C. with a solution of N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide(5.40 g, 34.8 mmol) in dichloromethane (10 ml) and stirred for 20 hs atroom temperature. The reaction mixture is concentrated in vacuo, and theoily residue is purified by column chromatography on silica gel withheptane/ethyl acetate mixture as eluent. The obtained product isrecrystallized from heptane/ethanol 1:1 to afford white crystals of 3(1.6 g, mp. 97° C.).

Example 4

Reactive mesogen 4 is prepared as follows.

4b is prepared with the exactly same method as described in 1b.

4c: To a solution of 4b (24.45 g, 63.0 mmol) and 4-bromo benzoic acid(12.8 g, 63.0 mmol) in 210 ml 1,4-dioxane was added 145 ml dist. water.Sodium carbonate (33.4 g, 31.0 mmol) is added. The resulted suspensionis degassed carefully with argon. Bis(triphenylphosphine)-palladium(II)chloride (0.88 g, 1.26 mmol) is then added, followed bytriphenylphosphine (0.33 g, 1.26 mmol) and triethylamine (0.18 ml, 1.26mmol). The reaction mixture is heated to reflux and stirred 3 hours.After cooling to room temperature, the reaction mixture is neutralizedcarefully with 6 M HCl acid under cooling to pH˜7. The precipitatedcrude product was filtrated and recrystallized from heptane/toluene 1:1to provide 4c as gray solid (21.8 g).

4d: To a solution of 4c (21.50 g, 55.0 mmol) in DMF (400 ml) is addedpotassium carbonate (9.17 g, 66.0 mmol). To the resulted suspension(2-bromo-ethoxymethyl)-benzene (19.20 g, 88.0 mmol) is added. Thereaction mixture is stirred at 70° C. overnight. After cooling to roomtemperature, the reaction mixture is added into 1000 ml water andextracted with 3×300 ml ethyl acetate. The organic phase is washed withsat. aq. NaCl solution, dried over sodium sulfate. After removingsolvent in vacuo, the oily residue is purified by column chromatographyon silica gel with dichloromethane as eluent to provide 4d as whitecrystal (23.9 g).

4e: A suspension of 4d (23.9 g, 45.0 mmol) in tetrahydrofuran (240 ml)is treated with palladium (5%) on activated charcoal (6.0 g) andsubmitted to hydrogenation for 30 hs. The catalyst is then filtered off.After removing solvent in vacuo, the solid residue is purified by columnchromatography on silica gel with toluene/heptane 1:1 as elute toprovide 4c as white solid (13.8 g).

4: Methacrylic acid (5.33 ml, 62.0 mmol) and 4-(dimethylamino)pyridine(0.26 g, 2.1 mmol) is added to a suspension of 4e (7.00 g, 20.0 mmol) indichloromethane (90 ml). The reaction mixture is treated dropwise at 0°C. with a solution of N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide(9.75 g, 62.0 mmol) in dichloromethane (20 ml) and stirred for 20 hs atroom temperature. The reaction mixture is concentrated in vacuo, and theoily residue is purified by column chromatography on silica gel withdichloromethane as eluent. The obtained product is recrystallized fromethyl acetate/heptane 1:2 to afford white crystals of 4 (4.7 g, mp. 72°C.).

In analogy to the methods described in Example 4, the following twocompounds are prepared.

Example 5

Example 6

Example 7

Reactive mesogen 7 is prepared as follows.

7b is prepared by the same method as described for compound 1b inExample 1.

7c: To a solution of 4-bromoresorcinol (30.0 g, 15.0 mmol) in DMF (250ml) is added potassium carbonate (4.32 g, 31.0 mmol). To the resultedsuspension ethylene carbonate (34.20 g, 39.0 mmol) is added. Thereaction mixture is heated to reflux and stirred overnight. Aftercooling to room temperature, the reaction mixture is added into 1000 mlwater and extracted with 3×300 ml ethyl acetate. The organic phase iswashed with sat. aq. NaCl solution, dried over sodium sulfate. Afterremoving solvent in vacuo, the oily residue is purified by columnchromatography on silica gel with ethylacetate as eluent to provide 7cas white crystal (31.3 g).

7d: To a solution of 7b (14.27 g, 36.0 mol) and 7c (9.4 g, 33.0 mmol) in400 ml 1,4-dioxane was added 38.5 g (167.0 mmol) potassium phosphate.The resulted suspension is degassed carefully with argon.Tris(dibenzylidene acetone)dipalladium(0) (0.61 g, 0.67 mmol) and2-dicyclohexylphosphine-2′,6′-dimethoxylbiphenyl (SPhos) (1.13 g, 2.68mmol) is then added. The reaction mixture is heated to reflux andstirred overnight. After cooling to room temperature 700 ml dist. waterand 300 ml ethylacetate are added, and the mixture is neutralizedcarefully with 6 M HCl acid under cooling to pH˜4. The aqueous phase isextracted with ethylacetate. The organic phase is combined and washedwith sat. aq. NaCl solution, dried over sodium sulfate. After removingsolvent in vacuo, the solid residue is purified by column chromatographywith ethyl acetate as eluent to provide 7d as light brown solid (8.5 g).

7e: A suspension of 7d (8.4 g, 18.1 mmol) in tetrahydrofuran (80 ml) istreated with palladium (5%) on activated charcoal (1.5 g) and submittedto hydrogenation for 20 hs. The catalyst is then filtered off. Afterremoving solvent in vacuo, the solid residue is purified by columnchromatography on silica gel with THF as elute to provide 7e asyellowish oil (7.7 g).

7: Methacrylic acid (4.50 ml, 53.0 mmol) and 4-(dimethylamino)pyridine(0.16 g, 1.3 mmol) is added to a suspension of 7e (5.00 g, 13.2 mmol) indichloromethane (50 ml). The reaction mixture is treated dropwise at 0°C. with a solution of N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide(8.23 g, 53.0 mmol) in dichloromethane (20 ml) and stirred for 20 hs atroom temperature. The reaction mixture is concentrated in vacuo, and theoily residue is purified by column chromatography on silica gel withdichloromethane as eluent. The obtained product is recrystallized fromethanol/heptane 6:1 to afford white crystals of 7 (4.1 g, mp. 83° C.).

Mixture Example 1

The nematic LC host mixture 1 is formulated as follows.

CCH-501 9.00% cl.p. 70.0° C. CCH-35 14.00% Δn 0.0825 PCH-53 8.00% Δε−3.5 PCH-304FF 14.00% ε_(||) 3.5 PCH-504FF 13.00% K₃/K₁ 1.00 CCP-302FF8.00% γ₁ 141 mPa s CCP-502FF 8.00% V₀ 2.10 V CCP-21FF 9.00% CCP-31FF9.00% CPY-2-O2 8.00%

Four polymerizable mixtures are prepared by adding each one of RM1 toRM4, respectively, to nematic LC host mixture 1 at a concentration of0.3% by weight.

Mixture Example 2

The nematic LC host mixture 2 is formulated as follows.

CY-3-O2 18.00% cl.p. +74.5° C. CPY-2-O2 10.00% Δn 0.1021 CPY-3-O2 10.00%Δε −3.1 CCY-3-O2 9.00% ε_(||) 3.5 CCY-4-O2 4.00% K₃/K₁ 1.16 CC-3-V40.00% γ₁ 86 mPa s PYP-2-3 9.00% V₀ 2.29 V

Four polymerizable mixtures are prepared by adding each one of RM1 toRM4, respectively, to nematic LC host mixture 2 at a concentration of0.3% by weight.

Mixture Example 3

The nematic LC host mixture 3 is formulated as follows.

CC-3-V 20.00% cl.p. 74.5° C. CC-3-V1 10.00% Δn 0.1084 CCH-34 8.00% Δε−3.2 CCH-35 4.00% V₀ 2.33 V CCY-3-O1 5.50% K₃/K₁ 1.04 CCY-3-O2 12.00% γ₁94 mPa s CPY-2-O2 2.00% CPY-3-O2 12.00% PY-3-O2 15.00% PY-4-O2 8.50%PYP-2-3 3.00%

Four polymerizable mixtures are prepared by adding each one of RM1 toRM4, respectively, to nematic LC host mixture 3 at a concentration of0.3% by weight.

Mixture Example 4

The nematic LC host mixture 4 is formulated as follows.

CC-3-V 20.00% cl.p. 74.6° C. CC-3-V1 10.00% Δn 0.1042 CCH-35 9.00% Δε−3.1 CCP-3-1 7.00% V₀ 2.48 V CCY-3-O2 13.00% K₃/K₁ 1.13 CPY-3-O2 13.00%γ₁ 94 mPa s CY-3-O2 8.00% PY-3-O2 15.00% PY-4-O2 5.00%

Four polymerizable mixtures are prepared by adding each one of RM1 toRM4, respectively, to nematic LC host mixture 4 at a concentration of0.3% by weight.

Mixture Example 5

The nematic LC host mixture 5 is formulated as follows.

CC-3-V 27.50% cl.p. 74.8° C. CC-3-V1 7.50% Δn 0.0986 CCH-23 3.00% Δε−3.4 CCP-3-1 3.75% V₀ 2.26 V CCY-3-O2 12.50% K₃/K₁ 1.16 CPY-2-O2 11.50%γ₁ 95 mPa s CPY-3-O2 10.50% CY-3-O2 15.50% PY-3-O2 3.00% PY-4-O2 5.25%

Four polymerizable mixtures are prepared by adding each one of RM1 toRM4, respectively, to nematic LC host mixture 5 at a concentration of0.3% by weight.

Mixture Example 6

The nematic LC host mixture 6 is formulated as follows.

CC-3-V 41.50% cl.p. 74.6° C. CCP-3-1 2.00% Δn 0.0983 CCY-3-O1 5.25% Δε−3.1 CCY-3-O2 12.50% V₀ 2.28 V CPY-2-O2 12.25% K₃/K₁ 1.11 CPY-3-O2 7.50%γ₁ 85 mPa s CY-3-O2 5.50% PY-3-O2 3.50% PY-4-O2 10.00%

Four polymerizable mixtures are prepared by adding each one of RM1 toRM4, respectively, to nematic LC host mixture 6 at a concentration of0.3% by weight.

Mixture Example 7

The nematic LC host mixture 7 is formulated as follows.

CC-3-V 27.50% cl.p. 75.6° C. CC-3-V1 8.00% Δn 0.0989 CCH-23 2.50% Δε−3.4 CCP-3-1 3.00% V₀ 2.28 V CCY-3-O2 12.00% K₃/K₁ 1.16 CCY-4-O2 2.00%γ₁ 94 mPa s CPY-2-O2 10.00% CPY-3-O2 10.50% CY-3-O2 15.50% CY-3-O4 1.00%PY-3-O2 15.00% PY-4-O2 7.00% PYP-2-3 1.00%

Four polymerizable mixtures are prepared by adding each one of RM1 toRM4, respectively, to nematic LC host mixture 7 at a concentration of0.3% by weight.

Mixture Example 8

The nematic LC host mixture 8 is formulated as follows.

CC-3-V 41.50% cl.p. 74.5° C. CCY-3-O1 2.50% Δn 0.0984 CCY-3-O2 11.50% Δε−3.3 CCY-3-O3 5.00% V₀ 2.29 V CPY-2-O2 5.00% K₃/K₁ 1.15 CPY-3-O2 12.00%γ₁ 89 mPa s CY-3-O2 9.50% PY-3-O2 7.00% PY-4-O2 3.00% PYP-2-3 3.00%

Four polymerizable mixtures are prepared by adding each one of RM1 toRM4, respectively, to nematic LC host mixture 8 at a concentration of0.3% by weight.

Mixture Example 9

The nematic LC host mixture 9 is formulated as follows.

CC-3-V 28.00% cl.p. 74.9° C. CCY-3-O1 10.00% Δn 0.1026 CCY-3-O2 1.00% Δε−3.0 CCY-3-O3 6.00% V₀ 2.47 V CPY-2-O2 12.00% K₃/K₁ 1.19 CPY-3-O2 3.00%γ₁ 90 mPa s CY-3-O2 12.00% PY-3-O2 10.00% PY-4-O2 15.00% PYP-2-3 3.00%

Four polymerizable mixtures are prepared by adding each one of RM1 toRM4, respectively, to nematic LC host mixture 9 at a concentration of0.3% by weight.

Mixture Example 10

The nematic LC host mixture 10 is formulated as follows.

CC-3-V 15.00% cl.p. 74.4° C. CC-3-V1 9.00% Δn 0.1086 CCH-23 8.00% Δε−3.2 CCH-34 7.50% V₀ 2.33 V CCY-3-O2 10.00% K₃/K₁ 1.10 CCY-5-O2 8.00% γ₁102 mPa s CPY-2-O2 3.00% CPY-3-O2 8.50% CY-3-O2 7.00% PY-3-O2 16.00%PYP-2-3 8.00%

Four polymerizable mixtures are prepared by adding each one of RM1 toRM4, respectively, to nematic LC host mixture 10 at a concentration of0.3% by weight.

Mixture Example 11

The nematic LC host mixture 11 is formulated as follows.

CC-3-V 42.00% cl.p. 73.5° C. CCY-3-O1 5.00% Δn 0.1007 CCY-3-O2 10.00% Δε−3.5 CCY-4-O2 2.50% V₀ 2.15 V CPY-2-O2 10.00% K₃/K₁ 1.13 CPY-3-O2 10.00%γ₁ 85 mPa s CY-3-O2 6.50% PY-3-O2 11.00% IS-18566 3.00%

Four polymerizable mixtures are prepared by adding each one of RM1 toRM4, respectively, to nematic LC host mixture 11 at a concentration of0.3% by weight.

Mixture Example 12

The nematic LC host mixture 12 is formulated as follows.

CC-3-V 45.50% cl.p. 73.0° C. CCY-3-O1 3.00% Δn 0.1011 CCY-3-O2 11.00% Δε−3.5 CCY-4-O2 3.50% V₀ 2.15 V CPY-2-O2 7.50% K₃/K₁ 1.09 CPY-3-O2 10.00%γ₁ 79 mPa s CY-3-O2 2.00% PY-3-O2 11.50% IS-18566 6.00%

Four polymerizable mixtures are prepared by adding each one of RM1 toRM4, respectively, to nematic LC host mixture 12 at a concentration of0.3% by weight.

Mixture Example 13

The nematic LC host mixture 13 is formulated as follows.

CC-3-V 34.50% cl.p. 75.0° C. CC-3-V1 8.00% Δn 0.1075 CCY-3-O1 7.00% Δε−3.1 CCY-3-O2 11.50% V₀ 2.41 V CCY-4-O2 3.50% K₃/K₁ 1.12 CPY-3-O2 11.50%γ₁ 84 mPa s PY-3-O2 13.00% PP-1-2V1 6.00% IS-18566 5.00%

Four polymerizable mixtures are prepared by adding each one of RM1 toRM4, respectively, to nematic LC host mixture 13 at a concentration of0.3% by weight.

Mixture Example 14

The nematic LC host mixture 14 is formulated as follows.

CC-3-V 37.50% cl.p. 75.5° C. CC-3-V1 7.00% Δn 0.1080 CCY-3-O1 6.00% Δε−3.0 CCY-3-O2 11.00% V₀ 2.41 V CPY-2-O2 4.50% K₃/K₁ 1.12 CPY-3-O2 11.00%γ₁ 84 mPa s PY-3-O2 17.00% PGIY-2-O4 5.00% PP-1-2V1 1.00%

Four polymerizable mixtures are prepared by adding each one of RM1 toRM4, respectively, to nematic LC host mixture 14 at a concentration of0.3% by weight.

Mixture Example 15

The nematic LC host mixture 15 is formulated as follows.

CC-3-V 39.00% cl.p. 75.0° C. CC-3-V1 7.00% Δn 0.1098 CCY-3-O1 1.50% Δε−3.0 CCY-3-O2 5.00% V₀ 2.41 V CPY-2-O2 9.00% K₃/K₁ 1.11 CPY-3-O2 6.00%γ₁ 82 mPa s PY-3-O2 11.50% PGIY-2-O4 16.00% PP-1-2V1 5.00%

Four polymerizable mixtures are prepared by adding each one of RM1 toRM4, respectively, to nematic LC host mixture 15 at a concentration of0.3% by weight.

Mixture Example 16

The nematic LC host mixture 16 is formulated as follows.

CY-3-O2 16.50% cl.p. 74.0° C. CCY-4-O2 10.50% Δn 0.1069 CCY-5-O2 6.00%Δε −3.2 CPY-2-O2 9.00% V₀ 2.18 CPY-3-O2 9.00% K₃/K₁ 1.06 CCH-34 9.00% γ₁117 mPa s CCH-31 20.00% CCP-3-1 2.00% PYP-2-3 6.50% PYP-2-4 6.50%PCH-301 5.00%

Four polymerizable mixtures are prepared by adding each one of RM1 toRM4, respectively, to nematic LC host mixture 16 at a concentration of0.3% by weight.

Mixture Example 17

The nematic LC host mixture 17 is formulated as follows.

CY-3-O2 16.50% cl.p. 74.5° C. CCY-4-O2 9.50% Δn 0.1070 CCY-5-O2 4.00% Δε−3.2 CPY-2-O2 9.00% V₀ 2.19 CPY-3-O2 9.00% K₃/K₁ 1.06 CCH-34 9.00% γ₁117 mPa s CCH-31 20.00% CCP-3-1 5.00% PYP-2-3 4.00% PYP-2-4 4.00%PCH-301 5.00% PGIY-2-O4 5.00%

Four polymerizable mixtures are prepared by adding each one of RM1 toRM4, respectively, to nematic LC host mixture 17 at a concentration of0.3% by weight.

Mixture Example 18

The nematic LC host mixture 18 is formulated as follows.

CY-3-O2 12.00% cl.p. 74.0° C. CY-3-O4 10.00% Δn 0.1064 CCY-3-O2 6.00% Δε−3.2 CCY-4-O2 6.50% V₀ 2.19 CCH-34 9.00% K₃/K₁ 0.99 CCH-35 5.00% γ₁ 119mPa s CCP-3-1 14.50% CCP-3-3 11.00% PYP-2-3 9.00% PYP-2-4 8.00% Y-4O-O49.00%

Four polymerizable mixtures are prepared by adding each one of RM1 toRM4, respectively, to nematic LC host mixture 18 at a concentration of0.3% by weight.

Mixture Example 19

The nematic LC host mixture 19 is formulated as follows.

CY-3-O2 12.00% cl.p. 73.5° C. CY-3-O4 10.00% Δn 0.1065 CCY-3-O2 6.00% Δε−3.3 CCY-4-O2 5.50% V₀ 2.18 CCH-34 8.50% K₃/K₁ 1.00 CCH-35 5.00% γ₁ 119mPa s CCP-3-1 15.00% CCP-3-3 11.50% PYP-2-3 5.50% PYP-2-4 5.00% PP-1-2V12.00% PGIY-2-O4 5.00% Y-4O-O4 9.00%

Four polymerizable mixtures are prepared by adding each one of RM1 toRM4, respectively, to nematic LC host mixture 19 at a concentration of0.3% by weight.

Mixture Example 20

The nematic LC host mixture 20 is formulated as follows.

CC-3-V 28.50% cl.p. 74.5° C. CCP-31 12.50% Δn 0.1077 CCOY-2-O2 19.00% Δε−3.2 CCOY-3-O2 11.50% V₀ 2.34 V PY-3-O2 13.50% K₃/K₁ 0.91 PP-1-3 10.00%γ₁ 99 mPa s PYP-2-3 5.00%

Four polymerizable mixtures are prepared by adding each one of RM1 toRM4, respectively, to nematic LC host mixture 20 at a concentration of0.3% by weight.

Mixture Example 21

The nematic LC host mixture 21 is formulated as follows.

CC-3-V1 9.00% cl.p. 75.4° C. CCH-23 14.00% Δn 0.1056 CCH-34 6.00% Δε−2.8 CCH-35 6.00% V₀ 2.67 V CCP-3-1 7.00% K₃/K₁ 1.07 CCY-3-O1 5.00% γ₁102 mPa s CCY-3-O2 10.00% CPY-3-O2 12.00% CY-3-O2 9.50% PP-1-2V1 8.50%PY-3-O2 12.00% PY-4-O2 1.00%

Four polymerizable mixtures are prepared by adding each one of RM1 toRM4, respectively, to nematic LC host mixture 21 at a concentration of0.3% by weight.

Mixture Example 22

The nematic LC host mixture 22 is formulated as follows.

CC-3-V 37.00% cl.p. 75.0° C. CC-3-V1 7.00% Δn 0.1090 CCY-3-O2 5.00% Δε−3.2 CLY-3-O2 10.00% V₀ 2.34 V CPY-2-O2 10.50% K₃/K₁ 1.14 CPY-3-O210.50% γ₁ 87 mPa s PY-1-O4 10.00% PY-3-O2 9.00% PGIY-2-O4 1.00%

Four polymerizable mixtures are prepared by adding each one of RM1 toRM4, respectively, to nematic LC host mixture 22 at a concentration of0.3% by weight.

Mixture Example 23

The nematic LC host mixture 23 is formulated as follows.

CC-3-V 34.50% cl.p. 74.5° C. CC-3-V1 8.00% Δn 0.1088 CCY-3-O1 9.00% Δε−3.2 CCY-3-O2 5.50% V₀ 2.33 V CLY-3-O2 10.00% K₃/K₁ 1.12 CPY-3-O2 5.00%γ₁ 90 mPa s PY-1-O4 10.00% PY-3-O2 10.00% PYP-2-3 3.00% PGIY-2-O4 5.00%

Four polymerizable mixtures are prepared by adding each one of RM1 toRM4, respectively, to nematic LC host mixture 23 at a concentration of0.3% by weight.

Mixture Example 24

The nematic LC host mixture 24 is formulated as follows.

B-2O-O5 5.00% cl.p. 74.6° C. CC-3-V1 38.00% Δn 0.1086 CCY-3-O1 10.00% Δε−3.2 CCY-3-O2 7.50% V₀ 2.34 V CLY-3-O2 10.00% K₃/K₁ 1.11 CPY-3-O2 9.50%γ₁ 82 mPa s PY-3-O2 13.00% PYP-2-3 2.00% PGIY-2-O4 5.00%

Four polymerizable mixtures are prepared by adding each one of RM1 toRM4, respectively, to nematic LC host mixture 24 at a concentration of0.3% by weight.

Mixture Example 25

The nematic LC host mixture 25 is formulated as follows.

CC-3-V 34.00% cl.p. 74.3° C. CC-3-V1 10.00% Δn 0.1091 CCY-3-O1 4.50% Δε−3.2 CLY-3-O2 10.00% V₀ 2.34 V CPY-2-O2 10.50% K₃/K₁ 1.12 CPY-3-O211.00% γ₁ 88 mPa s PY-1-O4 9.00% PY-3-O2 11.00%

Four polymerizable mixtures are prepared by adding each one of RM1 toRM4, respectively, to nematic LC host mixture 25 at a concentration of0.3% by weight.

For comparison purposes further individual polymerizable mixtures areprepared by adding direactive monomer Cl of prior art to each of nematicLC host mixtures 1-25 at a concentration of 0.3% by weight,respectively.

Use Examples

The polymerizable mixtures according to the invention and thepolymerizable comparison mixtures are each inserted into a VA e/o testcell. The test cells comprise a VA-polyimide alignment layer(JALS-2096-R¹) which is rubbed antiparallel. The LC-layer thickness d isapprox. 4 μm.

Each test cell is irradiated with UV light having an intensity of 100mW/cm² for the time indicated with application of a voltage of 24V_(rms) (alternating current), causing polymerization of thepolymerizable monomeric compound.

The VHR values of the polymerizable mixtures before and after UVexposure are measured as described above. The VHR values of the mixturesare shown in Table 1.

TABLE 1 VHR values Host Host Host Host Host Host 1 + 1 + 1 + 1 + 1 + 1 +C1 RM1 RM2 RM3 RM4 RM5 VHR/% 0 min UV 98.2 98.2 98.9 98.2 99.0 98.9 2 h98.1 98.2 98.6 98.2 98.8 98.9 Suntest¹⁾ Host Host Host Host Host Host2 + 2 + 2 + 2 + 2 + 1 + C1 RM1 RM2 RM3 RM4 RM5 VHR/% 0 min UV 96.4 97.198.2 98.4 98.7 98.7 2 h 86.5 84.2 89.8 89.6 91.5 95.0 Suntest¹⁾ 10 minUV 79.6 84.0 87.7 88.6 89.9 94.4 ¹⁾“Suntest” means a second irradiationstep with lower UV intensity but longer exposure time than the firststep.

As can be seen from Table 1, the VHR values of polymerizable mixturescomprising RM1 to RM5 according to the present invention after UVexposure are higher than the VHR values of polymerizable mixturecomprising monomer C1, especially in polymerizable mixtures comprisinghost mixture 2 with alkenyl compounds.

In addition, RM1 to RM5 according to the present invention do eithershow only a very small decrease or even an increase of the VHR after 2hsuntest compared to the initial VHR value.

In order to determine the polymerization rate, the residual content ofunpolymerized RM (in % by weight) in the test cells is measured by HPLCafter various exposure times. For this purpose each mixture ispolymerized in the test cell under the stated conditions. The mixture isthen rinsed out of the test cell using MEK (methyl ethyl ketone) andmeasured.

The residual concentrations of the respective monomer in the mixtureafter different exposure times are shown in Table 2.

TABLE 2 Residual monomer content Host 1 + Host 1 + Host 1 + Time/ C1 RM4RM5 min Residual RM/% 0 0.300 0.300 0.300 2 0.268 0.241 0.242 4 0.2360.158 0.153 6 0.200 0.132 0.133 Host 2 + Host 2 + Host 2 + Time/ C1 RM4RM5 min Residual RM/% 0 0.300 0.300 0.300 2 0.219 0.205 0.192 6 0.1070.088 0.072

As can be seen from Table 2, significantly more rapid and completepolymerization is achieved in PSA displays containing a polymerizablemixture with RM4 or RM5 according to the present invention, compared toPSA displays containing a polymerizable mixture with monomer Cl.

The tilt angle is determined before and after UV irradiation by acrystal rotation experiment (Autronic-Melchers TBA-105).

The tilt angles are shown in Table 3.

TABLE 3 Tilt angles Host Host Host + Host 1 + Host 1 + Host 1 + 1 + 1 +UV-Time/ C1 RM1 RM2 RM3 RM4 RM5 sec Pretilt Angle/° 0 89.0 88.6 88.588.6 89.2 89.0 30 88.8 88.8 86.9 87.4 88.2 88.8 60 87.8 87.4 86.5 86.086.1 86.7 120 86.2 80.6 83.9 77.7 78.1 80.1 Host Host Host 2 + Host 2 +Host 2 + Host 2 + 2 + 2 + UV-Time/ C1 RM1 RM2 RM3 RM4 RM5 sec PretiltAngle/° 0 88.8 87.7 88.5 88.6 89.0 89.0 120 80.7 80.5 79.4 79.8 77.775.0

As can be seen from Table 3, a small tilt angle after polymerization isachieved quickly in PSA displays containing a polymerizable mixture withRM1 to RM5 according to the present invention, which is smaller than ina PSA display containing a polymerizable mixture with monomer C1.

The preceding examples can be repeated with similar success bysubstituting the generically or specifically described reactants and/oroperating conditions of this invention for those used in the precedingexamples.

From the foregoing description, one skilled in the art can easilyascertain the essential characteristics of this invention and, withoutdeparting from the spirit and scope thereof, can make various changesand modifications of the invention to adapt it to various usages andconditions.

1. A compound of formula I

wherein R denotes P-Sp^(b)-, H or has one of the meanings given for L,Sp^(a), Sp^(b) denote, on each occurrence identically or differently, aspacer group or a single bond, P denotes, on each occurrence identicallyor differently, a polymerizable group, L F, Cl, CN, or straight chain,branched or cyclic alkyl having 1 to 25 C atoms, wherein one or morenon-adjacent CH₂-groups are optionally replaced by —O—, —S—, —CO—,—CO—O—, —O—CO—, —O—CO—O— in such a manner that O- and/or S-atoms are notdirectly connected with each other, and wherein one or more H atoms areeach optionally replaced by F or Cl, r is 0, 1, 2, 3 or 4, s is 0, 1, 2or 3, wherein at least one of the groups Sp^(a) and Sp^(b) is a singlebond and at least one of the groups Sp^(a) and Sp^(b) is different froma single bond.
 2. The compound of claim 1, wherein R is H or P-Sp^(b).3. The compound of claim 1, of the formula:


4. The compound according to claim 1, of the formula:

wherein Sp¹ is a spacer group.
 5. The compound according to claim 1,wherein P is an acrylate, methacrylate or oxetane.
 6. The compoundaccording to claim 1, wherein Sp¹, and Sp^(a) and Sp^(b) if not a singlebond, are —(CH₂)_(a)—, —(CH₂)_(a)—O—, —(CH₂)_(a)—CO—O—, or—(CH₂)_(a)—O—CO—, wherein a is 2, 3, 4, 5 or 6, and the O-atom or theCO-group, respectively, is connected to the aromatic ring.
 7. A liquidcrystal (LC) medium comprising one or more polymerizable compoundsformula I as defined in claim
 1. 8. The LC medium of claim 7, comprisinga polymerizable component A) comprising one or more polymerizablecompounds of formula I, and a liquid-crystalline LC component B)comprising one or more mesogenic or liquid-crystalline compounds.
 9. TheLC medium of claim 7, comprising one or more compounds of the formulaeCY and/or PY:

wherein a denotes 1 or 2, b denotes 0 or 1,

denotes

R¹ and R² each, independently of one another, denote alkyl having 1 to12 C atoms, where, in addition, one or two non-adjacent CH₂ groups maybe replaced by —O—, —CH═CH—, —CO—, —OCO— or —OCO— in such a way that Oatoms are not linked directly to one another, Z^(x) and Z^(y) each,independently of one another, denote —CH₂CH₂—, —CH═CH—, —CF₂O—, —OCF₂—,—CH₂O—, —OCH₂—, —CO—O—, —O—CO—, —C₂F₄—, —CF═CF—, —CH═CH—CH₂O— or asingle bond, and L¹⁻⁴ each, independently of one another, denote F, Cl,OCF₃, CF₃, CH₃, CH₂F, CHF₂.
 10. The LC medium according to claim 7,comprising one or more compounds of the following formulae:

in which individual radicals, on each occurrence identically ordifferently, each, independently of one another, have the followingmeaning:

R^(A1) alkenyl having 2 to 9 C atoms or, if at least one of the rings X,Y and Z denotes cyclohexenyl, also one of the meanings of R^(A2), R^(A2)alkyl having 1 to 12 C atoms, in which, in addition, one or twonon-adjacent CH₂ groups may be replaced by —O—, —CH═CH—, —CO—, —OCO— or—COO— in such a way that O atoms are not linked directly to one another,Z^(x) —CH₂CH₂—, —CH═CH—, —CF₂O—, —OCF₂—, —CH₂O—, —OCH₂—, —CO—O—, —O—CO—,—O₂F₄—, —CF═CF—, —CH═CH—CH₂O—, or a single bond, L¹⁻⁴ each,independently of one another, H, F, Cl, OCF₃, CF₃, CH₃, CH₂F or CHF₂H, x1 or 2, and z 0 or
 1. 11. The LC medium according to claim 7, comprisingone or more compounds of the following formula:

in which individual radicals have the following meanings:

denotes

denotes

R³ and R⁴ each, independently of one another, denote alkyl having 1 to12 C atoms, in which, in addition, one or two non-adjacent CH₂ groupsmay be replaced by —O—, —CH═CH—, —CO—, —O—CO— or —CO—O— in such a waythat O atoms are not linked directly to one another, Z^(y) denotes—CH₂CH₂—, —CH═CH—, —CF₂O—, —OCF₂—, —CH₂O—, —OCH₂—, —CO—O—, —O—CO—,—C₂F₄—, —CF═CF—, —CH═CH—CH₂O— or a single bond.
 12. The LC mediumaccording to claim 7, wherein the polymerizable compounds of formula Iare polymerized.
 13. A process of preparing an LC medium of claim 7,comprising mixing one or more mesogenic or liquid-crystalline compounds,with one or more compounds of formula I, and optionally with furtherliquid-crystalline compounds and/or additives.
 14. An LC displaycomprising one or more compounds of formula I as defined in claim
 1. 15.The LC display of claim 14, which is a PSA display.
 16. The LC displayof claim 15, which is a PS-VA, PS-OCB, PS-IPS, PS-FFS, PS-UB-FFS,PS-posi-VA or PS-TN display.
 17. The LC display of claim 15, comprisingtwo substrates, at least one which is transparent to light, an electrodeprovided on each substrate or two electrodes provided on only one of thesubstrates, and located between the substrates a layer of an LC medium,comprising one or more polymerizable compounds of formula I, wherein thepolymerizable compounds are polymerized between the substrates of thedisplay.
 18. A process for the production of an LC display according toclaim 17, comprising providing an LC medium, comprising one or morepolymerizable compounds, of formula I, between the substrates of thedisplay, and polymerising the polymerizable compounds.
 19. A compoundaccording to claim 1, of formula II

R′ denotes H or Pg-Sp^(b), and Pg denotes OH, a protected hydroxyl groupor a masked hydroxyl group.
 20. A process for preparing a compound offormula I of claim 1, wherein P denotes acrylate or methacrylate, byesterification of a compound of formula II

wherein Pg denotes OH, and R′ denotes H or Pg-Sp^(b) using correspondingacids, acid derivatives, or halogenated compounds containing a group P,in the presence of a dehydrating reagent.